2C-*-S190-EPLesson 2C - Weather

2C-*-S190-EPLesson Objectives1.Describe the affect of temperature and relative humidity has on wildland fire behavior.2.Describe the affect of precipitation on wildland fire behavior. 3.Describe the differences between a stable and unstable atmosphere.4.Describe general and local winds.Describe critical fire weather conditions. List the different types of fire weather forecasts and outlooks available.

2C-*-S190-EPFire Weather*Click on image to play video

2C-*-S190-EPAir TemperatureIn weather we refer to this as air temperature or dry bulb temperature.The degree of hotness or coldness of a substance.An average of the thermal energy of a group of particles in a substance (does not depend on # of particles)

2C-*-S190-EPTemperature is measured with a thermometer calibrated either to the FAHRENHEIT scale or the CELSIUS or centigrade scale. What influences air temperature?Time of daySeasonElevationTopographyLatitudeWeather systemsBodies of waterWhy does air temperature matter in wildland fires?

2C-*-S190-EPRelative HumidityFor a given air temperature, relative humidity (%) is the amount of moisture in the air divided by the amount the air could hold when saturated; usually expressed in percent.Ranges from 1-100%...what does 100% mean?

2C-*-S190-EP3 grams of H2O3 grams3 gramsTemperature and RH Relationships50F70F90F100%(saturated)50%(unsaturated)25%(unsaturated)

2C-*-S190-EPThermographTemperature and RH Relationship

2C-*-S190-EPTemperature vs. RH (general) for a given volume of airTemperatureRelative Humidity

2C-*-S190-EPSo what?Think of the fire triangleswhat does RH affect? Does this differ between fine/large fuels?Why does this matter for wildland fire suppression?Why does this matter for prescribed burning?Small changes in RH that arent noticed can have significant impactsWhat should you do on a fire?Monitoring = belt weather kit

2C-*-S190-EPPrecipitationPrecipitation is liquid or solid water particles that originate in the atmosphere, and become large enough to fall to the earths surface.

2C-*-S190-EPPrecipitationAmount vs. DurationFine Fuelsgain and lose moisture quicklyreact rapidly to precipitationHeavy Fuels gain and lose moisture slowlyreact slowly to precipitationDuration vs. AmountPrecipitation duration has greater impact on fuel moisture than precipitation amount

2C-*-S190-EPAtmospheric StabilityThe degree to which vertical motion in the atmosphere is ENHANCED or SUPPRESSED. *Click on image to play video

2C-*-S190-EPStable AtmosphereStable atmosphere resists upward vertical motion*Click on image to play video

2C-*-S190-EPStable AtmosphereVisual IndicatorsVisual IndicatorsClouds form in layersSmoke drifts apart after limited risePoor visibility due to smoke or hazeFog layersSteady winds

2C-*-S190-EPStable AtmosphereVisual Indicator ExamplesClouds form in layers

2C-*-S190-EPStable AtmosphereVisual Indicator ExamplesSmoke drifts apart after limited rise

2C-*-S190-EPStable AtmosphereVisual Indicator ExamplesPoor visibility due to smoke or haze

2C-*-S190-EPStable AtmosphereVisual Indicator ExamplesFog Layers

2C-*-S190-EPStable AtmosphereVisual Indicator ExamplesSteady Winds

2C-*-S190-EPStable Atmosphere Inversion*Click on image to play video

2C-*-S190-EPStable Atmosphere Inversion TypesFour Inversion TypesNighttime (Radiation)FrontalMarineSubsidenceTwo most common typesNighttime (Radiation)Subsidence

2C-*-S190-EPStable Atmosphere Nighttime Inversion*Click on image to play video

2C-*-S190-EPStable Atmosphere Thermal BeltThermal BeltNighttime inversions in mountainous regionsThe warm layer typically found on the middle third of the slopeCharacterized by the highest minimum temperature and lowest minimum RHFire can be very active within the thermal belt

2C-*-S190-EPStable AtmosphereSubsidence Inversion*Click on image to play video

2C-*-S190-EPSubsidence InversionMay persist for several daysMay reach the surface further enhancing fire activityTypically results inclear or cloudless skiesabove average temperatureslow relative humiditydrying of fuelsStable AtmosphereSubsidence Inversion Facts

2C-*-S190-EPUnstable AtmosphereEncouraging upward vertical motion

2C-*-S190-EPUnstable AtmosphereVisual IndicatorsVisual IndicatorsClouds grow vertically and smoke rises to great heightsCumulus cloudsGood visibilityGusty windsDust devils and firewhirls

2C-*-S190-EPUnstable AtmosphereVisual Indicator ExamplesClouds grow vertically and smoke rises to great heights

2C-*-S190-EPUnstable AtmosphereVisual Indicator ExamplesCumulus CloudsGood Visibility

2C-*-S190-EPUnstable AtmosphereVisual Indicator ExamplesGusty WindsDust devils and firewhirls*Click on image to play video

2C-*-S190-EPWindsHorizontal movement of air*Click on image to play video

2C-*-S190-EPWind impacts the fire environment by:Increasing the supply of oxygen to the fire.Determining the direction of fire spread.Increasing the drying of the fuels.Carrying sparks and firebrands ahead of the main fire causing new spot fires.Bending flames, which results in the preheating of fuels ahead of the fire.Influencing the amount of fuel consumed by affecting the residence time of the flaming front of the fire. The stronger the wind, the shorter the residence time and the less fuel is consumed. WindsWinds Effect on Wildland Fire

2C-*-S190-EPGeneral Winds*Click on image to play video

2C-*-S190-EPLocal Winds*Click on image to play video

2C-*-S190-EPLocal WindsSlope WindsUpslope WindsA result of differential heating and convective processes along the slope Average speeds range from 3 to 8 mphDevelop along east facing slope first and south and west facing slope by late morningDownslope WindsAir along the slope cools and sinks producing the downslope windAverage speeds range from 2 to 5 mphDevelop on east facing aspects first and south and west facing aspects after sunset

2C-*-S190-EPLocal WindsValley WindsUpvalley WindsAs the air warm, temperature and pressure differences within the valley or adjacent valleys result in upvalley wind flow. Strongest mid to late afternoon.Average speeds range from 10 to 15 mph. Downvalley WindsAs the valley loses solar heating, the air in the valley cools.The cool air drains downvalley.Average downvalley wind speeds range from 5 to 10 mph.Typically develop a few hours after sunset.

2C-*-S190-EPLocal WindsSea/Land Breeze

2C-*-S190-EPSea Breeze1998 Perry FireSea breeze interacting with Perry fire. Fire activity increases when sea breeze front penetrates fire.

2C-*-S190-EPUsed in Rx prescriptionsLVORI- Low Visibility Occurrence Risk IndexSmog index- risk of low visibility (vehicles)Increases with RH, and low DIFrom operational experience, one should be VERY CAUTIOUS ABOUT BURNING if one of the following situations occurs:When LVORI for a nighttime forecast period is 8,9 or 10 When ACTIVE SMOKE from stumps logs, etc. is present during the night When there is a roadway within three miles of a burn site with open fields, logging roads, or open streams that can provide an easy transit of the smoke from the burn site to the roadway

Table 1: Low Visibility Occurrence Risk Index (LVORI)

LVORI Category

Interpretation

1

Lowest proportion of accidents with smoke and/or fog reported (130 of 127,604 accidents, or just over 0.0010 accidents.)

2

Physical or statistical reasons for not including in category 1, but proportion of accidents not significantly higher.

3

Higher proportion of accidents than category 1, by about 30% to 50%, but of marginal significance (1%-5%).

4

Significantly higher than category 1, by a factor of 2.

5

Significantly higher than category 1, by a factor of 3 to 10.

6

Significantly higher than category 1, by a factor of 10 to 20.

7

Significantly higher than category 1, by a factor of 20 to 40.

8

Significantly higher than category 1, by a factor of 40 to 75.

9

Significantly higher than category 1, by a factor of 75 to 125.

10

Significantly higher than category 1, by a factor of 150.

2C-*-S190-EPDispersion Index Estimates daytime and nightime stability of the atmosphere. Higher DI = greater mixing, but very high = potential fire control problemsDoubling of the DI results in a doubling of the amount of smoke the airshed can holdRX : 41-70Under 30, could be OKif small unit with little smoke, or stagnant if winds are lowOver 71: very good dispersionbut hazardous to burn

Used in Rx prescriptions

2C-*-S190-EPThose who know how to read and heed weather!Those who think they can weather it all

2C-*-S190-EP2008 burnWinter AnnualACMF

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2C-*-S190-EPReview Lesson Objectives1.Describe the affect of temperature and relative humidity has on wildland fire behavior.2.Describe the affect of precipitation on wildland fire behavior. 3.Describe the differences between a stable and unstable atmosphere.4.Describe general and local winds.Describe critical fire weather conditions. List the different types of fire weather forecasts and outlooks available.

2C-*-S190-EPCritical Fire Weather*Click on image to play video

2C-*-S190-EPCritical Fire WeatherCold Fronts*Click on image to play video

2C-*-S190-EPCritical Fire WeatherFoehn Winds*Click on image to play video

2C-*-S190-EPMeteorologySanta Ana winds are a type of drainage wind, an offshore wind that results from the buildup of air pressure in the high-altitude Great Basin between the Sierra Nevada and the Rocky Mountains. When upper level winds are favorable, this high altitude air mass spills out of the Great Basin and is propelled gravitationally towards the southern California coastline, generally as a northeasterly wind.It is often said that the air is heated and dried as it passes through the Mojave and Sonoran deserts, but according to meteorologists this is a popular misconception. The Santa Ana winds usually form during autumn and early spring when the surface air in the elevated regions of the Great Basin and Mojave Desert (the "high desert") becomes cool or even cold, although they may form at virtually any time of year. The air heats up due to adiabatic heating during its descent. While the air has already been dried by orographic lift before reaching the Great Basin as well as by subsidence from the upper atmosphere, the relative humidity of the air is further decreased as it descends from the high desert toward the coast, often falling below 10 percent.The air from the high desert is initially relatively dense owing to its coolness and aridity, and thus tends to channel down the valleys and canyons in gusts which can attain hurricane force at times. As it descends, the air not only becomes drier, but also warms adiabatically by compression. The southern California coastal region gets some of its hottest weather of the year during autumn while Santa Ana winds are blowing. During Santa Ana conditions it is typically hotter along the coast than in the deserts. QuikSCAT image showing the speed of the Santa Ana winds (m/s).Note that while the Santa Ana Winds are an adiabatic wind, they are not a Fhn wind. A Fhn wind results from precipitation on the windward side of a mountain range which releases latent heat into the atmosphere which is then warmer on the leeward side (e.g. the Chinook or the original Fhn). The Santa Ana winds do not originate in precipitation, but in the bone-dry high deserts.The combination of wind, heat, and dryness accompanying the Santa Ana winds turns the chaparral into explosive fuel feeding the infamous wildfires for which the region is known. Wildfires fanned by Santa Ana winds burned 721,791 acres (2,921km) in two weeks during October 2003.[1] These same winds have contributed to the fires that have burned some 426,000acres (1,720km2) as of late October 2007.[2]Although the winds often have a destructive nature, they have some positive benefits as well. They cause cold water to rise from below the surface layer of the ocean, bringing with it many nutrients that ultimately benefit local fisheries. As the winds blow over the ocean, sea surface temperatures drop about 4C (7F), indicating the upwelling. Chlorophyll concentrations in the surface water go from negligible, in the absence of winds, to very active at more than 1.5 milligrams per cubic meter in the presence of the winds.

2C-*-S190-EPCritical Fire WeatherFoehn WindsCommon Foehn WindsChinookWasatchNorthEastSanta Ana

2C-*-S190-EPSan Diego, Oct. 2007Californias love the Santa Ana winds

2C-*-S190-EPCritical Fire WeatherThunderstorms

2C-*-S190-EPCritical Fire WeatherDust Devils and Firewhirls*Click on image to play video

2C-*-S190-EPComplete Exercise 4

2C-*-S190-EPPredictive ServicesPredictive ServicesProducts Produce By:Agency Fire MeteorologistsIntelligence CoordinatorFBANFuels Specialists

Monitors, analyzes and predicts Fire weatherFire dangerInteragency fire management resource impact

2C-*-S190-EPPredictive Services (national, regional websites)Predictive Services7 Day Significant Fire PotentialProduced WeeklyDaily in 200630 Day Fire PotentialProduced MonthlySeason Fire PotentialProduced AnnuallySpringFire Season UpdateSouthern Area Coordination Center

2C-*-S190-EPDOF Website: http://www.fl-dof.com/fire_weather/forecast/seasonal_forecast.htmlSeasonal Fire Weather Outlook: Updated January 4, 2008 January-March 2008Current Conditions Around Florida:The state began 2007 under neutral ENSO conditions but La Nia conditions formed later in the year. Dry conditions persisted through the fall due to the La Nia and positive Pacific North American (PNA) patternAccording to the U.S. Drought Monitor, most of the state is experiencing abnormally dry conditions with the south central part of the state seeing moderate to severe drought conditions.Long-range Outlook:The outlook for the next three months is for the current La Nia pattern to continue. Drought conditions are expected to worsenRainfall amounts are forecast to be near average by June and above average toward the end of the summer when we approach peak hurricane season. Summary:Drought conditions are expected to worsen over the spring months as the La Nia in the eastern Pacific Ocean persists. The potential will be high for another active wildfire season this spring once again. Longer term outlooks suggest summer rainfall could be influenced by another active hurricane season. The next forecast will be the first week in April, 2008. Should there be any questions, please contact Deborah Hanley at hanleyd@doacs.state.fl.us.

2C-*-S190-EPNational Weather ServiceNational Weather ServiceProducts produced for:Fire Weather ZonesProducts produced by:MeteorologistsProducts geared toward:Tactical planning

2C-*-S190-EPNWS: Fire Weather Planning ForecastA narrative or tabular zone-type productHere, will most likely be for JAXElements include:Sky/weatherTemperatureRelative humidityFNUS52 KJAX 171939FWFJAXFIRE WEATHER PLANNING FORECAST FOR NORTHEAST FLORIDA/SOUTHEAST GEORGIANATIONAL WEATHER SERVICE JACKSONVILLE FL239 PM EST THU JAN 17 2008DISCUSSION...

LOW PRESSURE WILL TRACK ACROSS THE FORECAST AREATHIS EVENING AND PUSH NORTHEAST OF THE REGION TONIGHT. SCATTEREDSHOWERS WILL DISSIPATE THROUGH THE EVENING HOURS. WEAK HIGH PRESSUREWILL BUILD INTO THE REGION ON FRIDAY. ANOTHER LOW WILL DEVELOP INTHE GULF OF MEXICO SATURDAY AND TRACK NORTHEAST OF THE REGIONSETTING THE STAGE FOR A COLD...BRISK AND DRY SUNDAY WITH HIGHPRESSURE SETTING UP OVER THE REGION EARLY NEXT WEEK.

RELATIVE HUMIDITIES WILL REMAIN ABOVE CRITICAL LEVELS THROUGH THE PERIODEXCEPT FOR SUNDAY WHEN RH VALUES WILL BOTTOM OUT IN THE 15-25 PERCENTRANGE OVER THE INLAND SECTIONS AND RED FLAG WARNINGS MAY BE REQUIRED.WINDS LESS THAN 15 MPH ARE EXPECTED ON FRIDAY. NORTHWEST WINDS OF15 TO 20 MPH ARE EXPECTED ON SATURDAY. NORTH WINDS OF 15 TO 20 MPHARE EXPECTED ON SUNDAY. NORTHEAST WINDS OF 15 TO 20 MPH WILLCONTINUE ON MONDAY AND SLOWLY DECREASE TO LESS THAN 15 MPH ONTUESDAY AND WEDNESDAY.GAZ153-154-165-166-181045-INLAND GLYNN-COASTAL GLYNN-INLAND CAMDEN-COASTAL CAMDEN-239 PM EST THU JAN 17 2008 TONIGHT FRI FRI NIGHT SATCLOUD COVER PCLDY PCLDY MCLDY MCLDYCHANCE PRECIP (%) 0 0 80 80WEATHER TYPE NONE SHOWERS SHOWERS SHOWERSTEMP 43 59 45 55RH (%) 97 60 100 7020FT WND MPH (AM) N 6 N 8 G2120FT WND MPH (PM) NW 8 N 4 NE 4 NW 14 G26PRECIP DURATION 11 11PRECIP BEGIN 7 PM CONTINUINGPRECIP END 7 AM CONTINUINGPRECIP AMOUNT 0.00 0.00 0.69 0.87LAL 1 1 1 1MIXING HEIGHT(FT-AGL) 500 2200 400 1600TRANSPORT WND (MPH) N 13 N 7 NE 7 NW 30DISPERSION INDEX 7 15 5 27MAX LVORI 6 9REMARKS...NONE..FORECAST FOR DAYS 3 THROUGH 7....SUNDAY...PARTLY CLOUDY. A 20 PERCENT CHANCE OF RAIN SHOWERS.LOWS IN THE UPPER 20S. HIGHS IN THE LOWER 50S. NORTHEAST WINDS15 TO 20 MPH..MONDAY...PARTLY CLOUDY. LOWS IN THE LOWER 30S. HIGHS IN THEUPPER 50S. NORTHEAST WINDS 10 TO 15 MPH..TUESDAY...MOSTLY CLOUDY. A 50 PERCENT CHANCE OF RAIN SHOWERS.LOWS IN THE MID 40S. HIGHS IN THE LOWER 60S. EAST WINDS 5 TO10 MPH..WEDNESDAY THROUGH THURSDAY...MOSTLY CLOUDY WITH A 50 PERCENTCHANCE OF RAIN SHOWERS. LOWS IN THE LOWER 50S. HIGHS IN THE UPPER 60S. SOUTHWEST WINDS 5 TO 15 MPH.

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Issued when the combination of dry fuels and weather conditions support extreme fire behavior or ignition is occurring or expected to occur.Can prevent prescribed burningNWS: Fire Weather Watches / Red Flag Warnings

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Issued when there is a high potential for the development of a Red Flag Event. Normally issued 24 to 72 hours in advance. Fire Weather WatchesFIRE WEATHER WATCH NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 946 AM CST FRI JAN 27 2006

...FIRE WEATHER WATCH IN EFFECT SATURDAY FOR THE GUADALUPE MOUNTAINS FOR RELATIVE HUMIDITIES OF 15 PERCENT OR LESS...SUSTAINED 20 FOOT WINDS OF 20 MPH OR GREATER AND HIGH FIRE DANGER...

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Used to warn of an impending, or occurring Red Flag event.

Red Flag WarningsRed Flag Warning/Fire Weather Watch Information

...RED FLAG WARNING IN EFFECT ACROSS THE SUWANNEE VALLEY REGION OF NORTH FLORIDA FROM NOON TO 5 PM EST THIS AFTERNOON FOR LONG DURATIONS OF LOW RELATIVE HUMIDITY...

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Site specific forecasts that are issued to fit time, topography and weather of a specific location.Spot Weather Forecast DOF in Florida must have local information and location

ForecastTimeTempHumidityWind SpeedDirectionCloud CoverPrecip5:0076-7985-90%3-6WNWBK6:0077-8084-89%3-6WNWBK7:0077-8083-88%4-7WNWBK8:0078-8183-88%4-7WNWBK9:0080-8378-83%4-7WNWBK10:0082-8574-79%4-7WNWBK11:0083-8670-75%4-7NWSC12:0084-8768-73%4-7SSWSC13:0085-8866-71%5-8ESESC12% Chance (Trace)14:0086-8964-69%5-8NBK15% Chance (Trace)15:0085-8865-70%5-8NNEBK12% Chance (Trace)

Florida Division of Forestry - Spot ForecastForecast ID: 1185873416 Date Issued: Tue Jul 31, 2007 at 05:16 Name: Leda Kobziar Company: University of Florida Location: 29.74 / -82.21

2C-*-S190-EPComplete Exercise 5

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