weather for the mariner lrg
TRANSCRIPT
Grunt Productions 2009
Weather for the Mariner
A Brief By Lance GrindleyA Brief By Lance Grindley
Grunt Productions 2009
Weather Tools Available
BarometerThermometerAnemometerNavtexWeather facsimileInternetE-MailVHF radio -- local area broadcastsHF radioCell phoneMK-1 eyeball
Grunt Productions 2009
Nautical Weather Sayings
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tall ships carry low sails First rise after very low indicates a stronger blow But what do they mean
Grunt Productions 2009
Marinerrsquos Rules of Thumb
In the mid latitudes weather systems (pressure centers)move from west to the eastbull Pressure Centers generally move in sequence with highpressure replaced by low pressure and low pressurereplaced by high pressurebull Be aware that your boat is moving relative to moving weathersystemsbull Pay attention to changes in cloud formation and the directionfrom which clouds approachbull Clouds are the marinerrsquos best visual indicator of changingweatherbull Pay attention to the direction of the true wind
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Observe the sea surface condition in relation to weatherconditions Gradually increasing ripples on the water arefirst indication of increasing wind
ndash Long parallel streaks in the water where foam andflotsamjetsam line up (called Langmuir Circulation) runsparallel with the wind and is a good indicator of true winddirection
ndash Generally warm moist air fuels low pressure So warmcurrents such as the Gulf Stream can cause dying lowpressure systems to redevelop and deepenndash Low Pressure systems are associated with storms andhigh pressure systems serve to block these storms
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Changes in air pressure wind direction humidityand temperature are excellent indicators ofchanging weather
If thermometers indicate that temperature and dewpoint differ by 5 degrees expect fog If temperatureand dew point differ by 3 degrees or less expectrain
Use Buys Ballotrsquos law to locate general location ofhigh and low pressure centers
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather Tools Available
BarometerThermometerAnemometerNavtexWeather facsimileInternetE-MailVHF radio -- local area broadcastsHF radioCell phoneMK-1 eyeball
Grunt Productions 2009
Nautical Weather Sayings
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tall ships carry low sails First rise after very low indicates a stronger blow But what do they mean
Grunt Productions 2009
Marinerrsquos Rules of Thumb
In the mid latitudes weather systems (pressure centers)move from west to the eastbull Pressure Centers generally move in sequence with highpressure replaced by low pressure and low pressurereplaced by high pressurebull Be aware that your boat is moving relative to moving weathersystemsbull Pay attention to changes in cloud formation and the directionfrom which clouds approachbull Clouds are the marinerrsquos best visual indicator of changingweatherbull Pay attention to the direction of the true wind
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Observe the sea surface condition in relation to weatherconditions Gradually increasing ripples on the water arefirst indication of increasing wind
ndash Long parallel streaks in the water where foam andflotsamjetsam line up (called Langmuir Circulation) runsparallel with the wind and is a good indicator of true winddirection
ndash Generally warm moist air fuels low pressure So warmcurrents such as the Gulf Stream can cause dying lowpressure systems to redevelop and deepenndash Low Pressure systems are associated with storms andhigh pressure systems serve to block these storms
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Changes in air pressure wind direction humidityand temperature are excellent indicators ofchanging weather
If thermometers indicate that temperature and dewpoint differ by 5 degrees expect fog If temperatureand dew point differ by 3 degrees or less expectrain
Use Buys Ballotrsquos law to locate general location ofhigh and low pressure centers
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Nautical Weather Sayings
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tall ships carry low sails First rise after very low indicates a stronger blow But what do they mean
Grunt Productions 2009
Marinerrsquos Rules of Thumb
In the mid latitudes weather systems (pressure centers)move from west to the eastbull Pressure Centers generally move in sequence with highpressure replaced by low pressure and low pressurereplaced by high pressurebull Be aware that your boat is moving relative to moving weathersystemsbull Pay attention to changes in cloud formation and the directionfrom which clouds approachbull Clouds are the marinerrsquos best visual indicator of changingweatherbull Pay attention to the direction of the true wind
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Observe the sea surface condition in relation to weatherconditions Gradually increasing ripples on the water arefirst indication of increasing wind
ndash Long parallel streaks in the water where foam andflotsamjetsam line up (called Langmuir Circulation) runsparallel with the wind and is a good indicator of true winddirection
ndash Generally warm moist air fuels low pressure So warmcurrents such as the Gulf Stream can cause dying lowpressure systems to redevelop and deepenndash Low Pressure systems are associated with storms andhigh pressure systems serve to block these storms
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Changes in air pressure wind direction humidityand temperature are excellent indicators ofchanging weather
If thermometers indicate that temperature and dewpoint differ by 5 degrees expect fog If temperatureand dew point differ by 3 degrees or less expectrain
Use Buys Ballotrsquos law to locate general location ofhigh and low pressure centers
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Marinerrsquos Rules of Thumb
In the mid latitudes weather systems (pressure centers)move from west to the eastbull Pressure Centers generally move in sequence with highpressure replaced by low pressure and low pressurereplaced by high pressurebull Be aware that your boat is moving relative to moving weathersystemsbull Pay attention to changes in cloud formation and the directionfrom which clouds approachbull Clouds are the marinerrsquos best visual indicator of changingweatherbull Pay attention to the direction of the true wind
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Observe the sea surface condition in relation to weatherconditions Gradually increasing ripples on the water arefirst indication of increasing wind
ndash Long parallel streaks in the water where foam andflotsamjetsam line up (called Langmuir Circulation) runsparallel with the wind and is a good indicator of true winddirection
ndash Generally warm moist air fuels low pressure So warmcurrents such as the Gulf Stream can cause dying lowpressure systems to redevelop and deepenndash Low Pressure systems are associated with storms andhigh pressure systems serve to block these storms
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Changes in air pressure wind direction humidityand temperature are excellent indicators ofchanging weather
If thermometers indicate that temperature and dewpoint differ by 5 degrees expect fog If temperatureand dew point differ by 3 degrees or less expectrain
Use Buys Ballotrsquos law to locate general location ofhigh and low pressure centers
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Observe the sea surface condition in relation to weatherconditions Gradually increasing ripples on the water arefirst indication of increasing wind
ndash Long parallel streaks in the water where foam andflotsamjetsam line up (called Langmuir Circulation) runsparallel with the wind and is a good indicator of true winddirection
ndash Generally warm moist air fuels low pressure So warmcurrents such as the Gulf Stream can cause dying lowpressure systems to redevelop and deepenndash Low Pressure systems are associated with storms andhigh pressure systems serve to block these storms
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Changes in air pressure wind direction humidityand temperature are excellent indicators ofchanging weather
If thermometers indicate that temperature and dewpoint differ by 5 degrees expect fog If temperatureand dew point differ by 3 degrees or less expectrain
Use Buys Ballotrsquos law to locate general location ofhigh and low pressure centers
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Marinerrsquos Rules of Thumb
Changes in air pressure wind direction humidityand temperature are excellent indicators ofchanging weather
If thermometers indicate that temperature and dewpoint differ by 5 degrees expect fog If temperatureand dew point differ by 3 degrees or less expectrain
Use Buys Ballotrsquos law to locate general location ofhigh and low pressure centers
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Air Masses
Air masses are vast bodies of air with uniformtemperature and moisture
Air is modified based upon itrsquos source region or inother words where the air is modified1048698 Modified to be1048698 Cold or warm1048698 Continental (dry air) or Maritime (moist air)
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Air Masses The types of air masses arendash Maritime polar cool and moistndash Arctic very cold and dryndash Continental polar cold and dryndash Continental tropical Hot and dryndash EquatorialMaritime tropical (always warm and moist)
Air Masses
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Air Pressure and PressureTrends
Barometers are instruments that measureair pressure
Barometric pressure is one of the best indicatorsof impending weather
Barometric pressure should be logged every 4hours along track
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Pressure is measured in millibars mb (read frominside dial used on weathercharts)
Inner scale on dialreads millibars
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Air Pressure and PressureTrends
1048698 Watching barometric pressure trends is oneof the best indicators of impending weather1048698 It is important to keep track of pressuretrendsndash use a 3 hour trend with a barometer1048698 Rapid pressure changes Over 6 mb fall (or rise) in 3 hours1048698 Moderate pressure changes 3-6 mb fall (or rise) in 3 hours1048698 Slow pressure changes 3 mb fall (or rise) in 3 hours
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Pressure
Two types of air pressure1048698 High pressure Think of high pressure as a mound or hill of air
1048698 Low pressure Think of low pressure as a depression of air
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Low Pressure
Air rises at the centre of low pressure
Air circulates around low pressure centres counter clockwise and pulls the surrounding air inward like a vacuum
Low pressure centres are the anchoring points for fronts950 mb is a very deep low pressure system (results in an intense storm)988 mb is a moderately deep low pressure system
Associate low pressure with storms or deteriorating weather
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
High Pressure
Air sinks at the centre of high pressure
Air circulates around high pressure centres clockwise and deflects the air outward
High pressure tends to block or deflect approaching bad weather
High pressure indicates fair and dry weather 1035 mb is a very strong high pressure centre 1012 is a moderately strong high pressure centre
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Wind and Pressure
Wind is the result of high and low pressure differences and the atmospherersquos attempt to equalize the pressure differencesair will flow from high pressure (mound of air) in toward the low pressure (depression of air)
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Wind and Pressure
The greater the pressure difference between high and low pressure the greater the wind speed
Wind direction is always indicated from the direction the wind is blowing
1048698 For example NE wind blows from the NE1048698 A southerly wind blows from the south
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Wind and Pressure
Isobars on a weather chart are contours of pressure around a high or low pressure centre
Isobars are indicated in millibars (mb)barometric Pressure is lowest at the centre of a lowbarometric Pressure is highest at the centre of a high
Tightly packed isobars on a weather chartindicate a strong gradient or wind
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Buys Ballot Law
Its important to know where the low pressure centre is located
This is thumb rule to use to locate the low pressure system relative to your location1048698 Stand with the wind at your back1048698 Turn 15 deg to your right1048698 Low pressure will be to your left and high pressure will be to your right
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Air Masses and Frontal Systems
When two different air masses collide the boundary of the collisionis called a front
Four Types of frontsndash Cold frontndash Warm frontndash Occluded frontndash Stationary front
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Cold Front
Cold Air pushes underneath warm air and causes the airto rise violently and rapidly
Cold fronts move fast 20- 35 kts
Generally move E-SE
Weather deteriorates rapidlyApproaching clouds seen 50 - 150 miles ahead of cold front
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Cold Front Weather
Heavy rain
Thunder and lightning
Tornados (not normally seen in UK)
Hail
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Cold Front Weather Sequence
Winds steady from SW1048698 Altocumulus (Ac) clouds (mid-level puffy clouds) on W or NW horizon1048698 Barometer pressure falls1048698 Clouds progressively lower andthicken1048698 Cumulonimbus (Cb) clouds orThunderheads form1048698 Symbol to mark the boundary of the front is a line with blue triangles(cold air is behind the line)
Cold front symbol
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Cold Front Weather Sequence
Squalls precede front by 5-6 hoursndash Intense black cloudsndash Violent gusty windsndash Cold blast of wind several miles ahead of front
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Cold Front Weather Sequence
As front passes weather is as followsndash Wind veers (moves clockwise) from SW to W-NWndash Barometer pressure at lowestndash Rain or squallndash Thunder and lightningndash Rapid clearing of skyndash Strong gusty winds from W-NWndash Air temperatures become colder
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Warm Front
Warm air slides over cold air1048698 Moves slowly 10-15kts1048698 Weather deteriorates gradually1048698 Approaching clouds seen from1000+ miles1048698 Symbol marking the front is aline with red half circles (warmair is behind the line)
Warm front symbol
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Warm Front Weather
Cirrus clouds (Ci) (high clouds) thicken to Cirrostratus(Cs) then Altostratus (mid-level) clouds then Ns (lowdark rain clouds)
Steady light rain
Persistent fog
Barometer pressure falls
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Warm Front WeatherSequence
Front passes gradually less intense than cold front
Wind veers (rotates clockwise) from S-SE to SW
Drizzle and fog may persist
Rain and thick clouds diminish
Air temperatures become warmer
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Occluded Front
Occurs when cold frontovertakes the warm front1048698 Weather is a combination ofcold steady misty rain anddrizzle1048698 Notice the symbol to markthe occluded front is a purplecombination of a cold andwarm front symbol
OccludedFrontsymbol
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Stationary Front
Occurs when the frontalboundary either moves veryslowly or does not move
1048698 Notice that the symbol marking the stationary front is alternating red half circle on the warm air side and blue triangles on the cold air side
Stationary front symbol
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Cape HatterasConditions for the ldquoPerfect Stormrdquo
Warm moist air from ocean currents will add fuel tolow pressure systems moving offshoreTherefore the warm sector of the Gulf Stream cancause a dying low pressure system moving off coastto redevelop
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Nautical Weather Sayings (Again)
Red sky at night sailorrsquos delight Red sky in the morning sailor take warning
Mackerel skies and marersquos tails make tallships carry low sails
First rise after very low indicates a strongerblow
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds
To understand some of these nautical weather rhymes we need to talk about clouds
Clouds are a marinerrsquos best visual indicatorof changing weather
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds
Clouds are classified by Height stratus (low) alto (mid-level) and cirrus (high- level) Texture cumulus (little white puffies) or stratus (flat)
Latin Translation Example
cumulusstratuscirrusaltonimbus
heaplayercurl of hairheight upper airrain
fair weather cumulusaltostratuscirrusaltocumuluscumulonimbus
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Forecasting weather using clouds
If clouds appear high and then thicken(cumuloform clouds) and lower a cold frontis approaching
If clouds appear high and then flatten outand lower (strataform clouds) a warm frontis approaching
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds
Cirrus Ci(High - Marersquos Tails)
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds
Altocumulus Ac(mackerel skies)
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds
Stratus(low flat)
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds
cumulus Cu (heap)
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds Cumulonimbus Cb (Thunderheads)extreme vertical extent from surface to~ 20000 - 35000 ftanvil top indicates strong wind shear
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds Cumulonimbus Cb
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Clouds Fog
Fog is a stratus cloud 50 ft or lessfrom the ground
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Red Sky at Night Sailorrsquos Delight
As the sun sets and moves lower in the skythe colours observed are those inthe longer wavelengthsof the spectrum (orange and red) At nightthe sun is in the western skyA red sky indicates clear weather inwest Since weather generally movesfrom west to east a red sky indicates that thewest is clear and there are no approachingweather making systems
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Red Sky in the MorninghellipSailor Take Warning
In the morning the sun risesabove the eastern horizonAnd the red colours observedare those in the longerwavelengths of the spectrumA red sky in the morningtherefore indicates clear weather in the east However since weather generally moves from west to east a red sky indicates that the east is clear and therefore deterioratingweather is approaching from the west
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Mackerel Skies and Marersquos Tails Make Tall Ships Carry Low Sails
Mackerel Skies (Altocumulus or cirrocumulus Clouds) andMarersquos Tails (Cirrus Clouds) indicate an approaching coldfront as warm air is rapidly pushed up in advance of the front
Marersquos tails (Cirrus)Mackerel Skies (altocumulus or cirrocumulus)
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
ldquoFirst rise after a very lowindicates a stronger blowrdquo
bull Refers to the rise in barometric pressure following aperiod of low pressure
bull Wind is caused by the difference between high andlow pressure and the atmospherersquos attempt to equalizethe two
bull The greater the pressure differences the strongerthe wind
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Other Weather resources
Internet weather charts obtained from1048698 internet prior to sailingndash wwwmetofficegovuk
1048698 Weather observations passed from otherboats
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
VHF Radio
Local area broadcasts are messages provided by MCA and provide
1 Current weather
2 Conditions and forecasts for specific areas
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
HF Radio
Voice Broadcasts are also located on HF frequencies (Check ALRS for specific HF frequencies and times of broadcast)
Caution Weather information is perishable
Information and local area broadcasts are good only for a SPECIFIC area at a SPECIFIC time
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather Charts via HF Facsimile
Weather Charts can be accessed via HF facsimile
bull Various weather charts are disseminated on a setschedule
bullALRS provides the schedule and HF frequenciesvia which these charts can be accessed
bull One can pre-program the Furuno WeatherFacsimile machine to automatically access the HFsignal at the time that these charts are broadcast
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather Charts
Weather charts are 2 dimensional depictionsof the atmosphere which is 3 dimensional
They are also snapshots in time
At sea weather charts are obtained by weather facsimile
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather Charts
Weather Charts can be divided into two types1048698 Analysis Charts (charts that tell you what theweather did)1048698 Prognostic (Forecasting) Charts (charts thattry to predict what the weather will do)
1048698 When reading a weather chart it is important to first checkndash Is it an analysis or prognostic chartndash If it is an analysis chart how old is the analysisndash If it is a prognostic chart when is the forecast valid
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather Charts
When reading a weather chart it is also important to determine if that analysis or prognostic chart gives you the surface weather information or if it gives you the upper level weather information
1048698 For the mariner the surface analysis or the surfaceprognostic chart provides the most usefulinformation
1048698 For aviators the upper level charts provideadditional useful information
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather Charts and Symbols
Surface weather charts will show cold warm occluded and stationary frontal boundaries
Wind barbs which indicate wind directionand speed are also shown and look like
Wind barbs are located on surface analysis charts and give the wind and weather conditions that occurred at various weatherstations
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Deciphering Wind Barbs
Wind barbs give information regardingndash Cloud coverndash Wind directionndash Wind speedndash Barometric pressurendash Air temperaturendash Dew point
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Deciphering Wind Barbs
Wind direction and speed (each long barb 10 kts short barb 5kts)Wind is from NE in this example
Air temp Barometric pressure
Cloud CoverDew point Cloud type
For Barometric Pressure0153 means 10153 mb803 means 9803 mb
(if 1st digit is 0 put a 1before it)(if 1st digit is 567 8 or9 put a 9 before it)
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Weather charts and windSome weather charts may not show wind barbs
1048698 Wind can also be determined by looking atthe isobars (the lines of constant pressure)surrounding the low or high pressure
1048698 The tighter the spacing between isobars the strongerthe wind
1048698 Around a low pressure centre wind blows parallel but slightly crosses the isobars in toward low pressure1048698 Slightly inward and counter clockwise around a low
1048698 Around a high pressure centre wind blows parallel but slightly crosses the isobars outward from high pressure clockwise1048698 Slightly outward and clockwise around a high
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Wind Warnings
Gale Warnings 34 - 47 kts
1048698 A Gale Warning is issued to alert all mariners whenever sustained winds of 34 to 47 knots associated with anontropical system are either ongoing or forecasted to develop within the next 12 hours
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Wind Warnings
Storm Warnings 48 + kts
bull Sustained winds above 48 knots of nontropical (extratropical) origin Does not have closed cyclonic rotation
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Hurricane Warnings
Definite Closed Cyclonic (CCW) Rotation
Winds in this range associated with a system developing from a tropical depression would be covered under a Tropical Storm Warning (34 to 63 knots) Differs from a midlatitudes orextratropical storm in that it has a closed cyclonic (CCW) rotation
Tropical Depression gt34 kts
Tropical Storm Warning 34-63 kts
Hurricane Warnings 64 + kts
Atlantic Hurricane season lasts from June- Nov
Grunt Productions 2009
Questions
Grunt Productions 2009
Questions