dynamics of severe weather · airmass or “pop-up” thunderstorm. buoyancy driven. growing ......
TRANSCRIPT
Dynamics of Severe WeatherJoe Sienkiewicz
NOAA/NWS Ocean Prediction Center
with Ken PryorNOAA/NESDIS StAR
And training material from COMET MetEd sitehttps://www.meted.ucar.edu/
Outline
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1.Thunderstorm basics2.Discussion points3.Available sources of information
thunderstorm—(Sometimes called electrical storm.) In general, a local storm, invariably produced by a cumulonimbus cloud and always accompanied by lightning and thunder, usually with strong gusts of wind, heavy rain, and sometimes with hail.It is usually of short duration, seldom over two hours for any one storm.
A thunderstorm is a consequence of atmospheric instability and constitutes, loosely, an overturning of air layers in order to achieve a more stable density stratification. A strong convective updraft is a distinguishing feature of this storm in its early phases.
Byers, H. R., and R. R. Braham Jr., 1949: The Thunderstorm, U.S. Government Printing Office, 287 pp.
Byers, H. R., 1951: Compendium of Meteorology, p. 681.
http://www.ametsoc.org/amsedu/wes/glossary.html#T
Thunderstorm - definition
Global IR, 500 mb height, Lightning
GOES-E1745 3 Jul 2009
http://www.nhc.noaa.gov/satellite.shtml
GOES-E, LTNG (1 hr trace)1745 3 Jul 2009
Squall Lines Multi Cell Lines& Super cellsOutflow Boundaries
GOES-E, LTNG (1 hr trace)1745 3 Jul 2009
Wind OutflowBoundaries
GOES-E, LTNG1745 3 Jul 2009
Tropical Wave
GOES-E, LTNG1745 3 Jul 2009
Tropical ConvectionMore upright / Single to multi cell
Types of THUNDERSTORMS
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Single Cell Storm
Multicell cluster storm
Multicell line storm
Supercell stormhttps://www.meted.ucar.edu/training_module.php?id=816
https://www.meted.ucar.edu/training_module.php?id=18
Types of THUNDERSTORMS
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Single Cell Storm
• brief isolated downbursts …• can occur anywhere within the generally disorganized storm. • low predictability
Airmass or “Pop-Up” thunderstorm
Buoyancy driven
GROWING
MATURE
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CUMULUS CLOUDS
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Types of THUNDERSTORMS
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Multicell cluster storm
• downbursts … moderate size hail …• high winds more frequently near the updraft/downdraft interface on the rear (southwest) and front (east) storm quadrants (NH perspective)• moderate degree of predictability of severe events
Organized AirmassLonger lived than single cell
Buoyancy driven with some shearSEPARATE updraft/downdraft
Types of THUNDERSTORMS
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Multicell line storm
• downbursts… small to moderate size hail …• most frequently near the updraft/downdraft interface on the leading edge (east) storm quadrant, especially cells associated with breaks in the line (NH perspective)• Moderate degree of predictability of severe events
Highly organizedLonger lived than multicell
Instability and moderate/strong shearSEPARATE updraft/downdraft
SQUALL LINES
MAMMATUS
MAMMATUS
MAMMATUS
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LINE
MOVEMENT
CELL
MOVEMENT
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MAMMATUS
GREEN TINGEHAIL = strong updraft = strong downdraft 21
Bow Echo Vertical Cross Section
• a strong, vertically erect updraft at the leading edge of the system,
• a strong, elevated rear-inflow jet at mid-levels before descending rapidly to spread along the surface.
Bow Echoes Summary • 20-120 km long bow-shaped systems of convective cells
– producing long swaths of damaging surface winds
• Either isolated convective systems or squall line
• line-end vortices - bookend vortices
• Unstable environment in moderate to strong shear
• Rear Inflow Notch (RIN)– A weak echo notch behind the core of the bow, – often signifies the location of a strong rear-inflow jet
• tend to propagate in the direction of the mean low-level vertical wind shear vector
• vertically erect updraft at the leading edge of the system
• strong, elevated rear-inflow jet descending rapidly to the surface
Rear Inflow Notch (RIN) Examples
A RIN apparent behind the bowing segment
A sharply defined RIN
Types of THUNDERSTORMS
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Supercell storm
• strong downbursts … large hail …• always occur near the updraft/downdraft interface typicallyin rear (southwest) storm flank. Some supercells have theinterface on the front or southeast flank. • High predictability of occurrence of severe events once storm isidentified as a supercell.
Highly organizedCan be long lived
Strong instability / shearSEPARATE updraft/downdraftStorm splitters left and right movers
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Outflow phenomena
• DOWNBURSTA strong downdraft which includes an outburst of potentially damaging winds on or near the ground
• MACROBURST> 2.5 miles in diameter
• MICROBURST< or = 2.5 miles in diameter
Long lived Super Cell380 miles / 4 states~ 8 hours
Apr 27, 2011
Tuscaloosa
Supercells can morph to a bow echo
24 hr Radar Loop 16 -17 Apr, 2011
Link to animated gif of 24 hour loop
24 hr Radar Loop 26 -27 Jan, 2012
http://ftp.mpc.ncep.noaa.gov/ppt/Tall_Ships_2012/CNVTN_JAN_27.wmv
Watch how quicklystorms develop here
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• DOWNBURSTA strong downdraft which includes an outburst of potentially damaging winds on or near the ground
• MACROBURST> 2.5 miles in diameter
• MICROBURST< or = 2.5 miles in diameter
Outflow phenomena
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MICROBURSTS
CAPE – Convective Available Potential EnergyLCL – Lifted Condensation Level (CLOUD BASE)
Still Developing50k
40k
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20k
10k
Outflow
Outflow
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40k
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10k
Overshooting Top
Outflow
Outflow
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Precip CoreDescent
Overshooting Top Collapse
Outflow
Outflow
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40k
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10k
Precip CoreDescent
Outflow
Outflow
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40k
30k
20k
10k
Outflow
Outflow
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10k
Outflow
Outflow
http://ftp.mpc.ncep.noaa.gov/ppt/Tall_Ships_2012/Jul09_Tstorms.wmv
Jul 03, 2009 Thunderstorm activity60 min lightning history per color bar
THUNDERSTORM TIPSKnow the forecast!
NOAA WX Radio
Fronts, troughs, boundaries
Watch the sky!!! ACT EARLY!!!!PDA, Cell phone, laptop (NWS radar)
Beware of false sense of security!
Gulf Stream
Flow parallel to the Stream
Maximum activity at night
AM Radio, lightning activity
Radar (rain clutter/sea clutter)
If storm approaching quickly assume is embedded in
strong flow (potential for damaging winds)!!!!
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Discussion Points• Eyes to the sky (active weather), continually assess• Situational awareness optimized (integrated)• Have an expectation
– Evolution may be faster than anticipated– Mid level Alto Cu Castellanas may be an indication of trouble– Can see cloud layers – look for shear
• Know where you are (westerlies / tropics)• Tools aboard
– Broadband (email)– Weatherfax
• Pre-frontal troughs• Strong cold fronts
– Satellite sources– Discussions (if available)– Radar
• Likely only see leading edge of precip (3 cm wavelength)
Is there anything NOAA should be providing?
Sources of Information•NOAA NESDIS StAR Experimental Convective Downburst
http://www.star.nesdis.noaa.gov/smcd/opdb/kpryor/mburst/mbimg.html•NOAA NWS Aviation Center
http://aviationweather.gov/products/swh/• NOAA Storm Prediction Center
http://www.spc.noaa.gov/• NOAA National Hurricane Center
http://nhc.noaa.gov• NCAR Ocean Convection for Aviation Page
http://www.rap.ucar.edu/projects/ocn/ops/ • NASA Earth Science Office
http://www.ghcc.msfc.nasa.gov/GOES/
http://www.star.nesdis.noaa.gov/smcd/opdb/kpryor/mburst/mbimg.html
Future capabilities
GOES-R LightningCloud top height
Satellite based products (aviation)
http://aviationweather.gov/products/swh/
NCAR Ocean Convection for Aviation http://www.rap.ucar.edu/projects/ocn/ops
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2 hr 9 m loop / every 5 min