special severeweather & heavy rain weather briefing 03/19/2012 srh.noaa/shv/briefing
DESCRIPTION
Special SevereWeather & Heavy Rain Weather Briefing 03/19/2012 www.srh.noaa.gov/shv/briefing. Keith Stellman Warning Coordination Meteorologist. National Weather Service Shreveport, Louisiana. Overview. ** Significant Severe Weather and Rainfall Event Setting up across the region ** - PowerPoint PPT PresentationTRANSCRIPT
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Special Special SevereWeather SevereWeather & & Heavy Rain Heavy Rain Weather Weather
BriefingBriefing03/19/201203/19/2012
www.srh.noaa.gov/shv/briefingwww.srh.noaa.gov/shv/briefing
Keith StellmanKeith StellmanWarning Coordination Warning Coordination
MeteorologistMeteorologistNational Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana
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Overview****Significant Severe Weather and Rainfall Event Significant Severe Weather and Rainfall Event
Setting up across the regionSetting up across the region****
Setup:Setup: Cutoff – slow moving upper lowCutoff – slow moving upper low Stalled FrontStalled Front High Precipitable Water (99High Precipitable Water (99thth percentile) percentile) Soils prepped from the recent rainsSoils prepped from the recent rains
ImpactsImpacts Serious Flooding/Flash Flooding!!Serious Flooding/Flash Flooding!! Tues AM->Thu AMTues AM->Thu AM Severe Weather Threat Late Monday/Early Severe Weather Threat Late Monday/Early
TuesTues Damaging Winds – Strong!Damaging Winds – Strong! Tornadoes (primarily East TX/SE OK/SW AR)Tornadoes (primarily East TX/SE OK/SW AR)
National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana
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Current Satellite/Water Current Satellite/Water VaporVapor
National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana
L
Note the plume of moisture Note the plume of moisture from the Pacificfrom the Pacific
Strong Polar Jet diving Strong Polar Jet diving Down the backside of this lowDown the backside of this low
Strong ridge holding strong Strong ridge holding strong East of the areaEast of the area
H
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Radar @ 1045 AM Radar @ 1045 AM MondayMonday
Strong Strong Storms Storms developingdeveloping
Expect this Expect this line to line to shift east shift east slowly with slowly with stronger stronger stormsstorms
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Monday PMMonday PM Upper Upper
level low level low beginninbeginning to cut g to cut off.off.
Waves of Waves of storms storms moving moving across across west/NW west/NW areasareas
L
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7 PM 10 PM
1 AM 4 AM
MondayPM
Thru
Tuesday AM
Model RadarSimulation
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Precip Precip through through Tues 7 Tues 7
AMAM High High
Risk Risk of of excessivexcessive e rainfall rainfall i.e. i.e. Flash Flash FloodingFlooding
Excessive Rainfall Outlook
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SPC Mod
erat
e ris
k are
a
SPC Mod
erat
e ris
k are
aSevere Weather Threat – Monday PM/Tuesday AMSevere Weather Threat – Monday PM/Tuesday AM
Primary Threats:Primary Threats:1.1.Damaging WindsDamaging Winds2.2.TornadoesTornadoes
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Tuesday PMTuesday PM Front Front aligns aligns along along Sabine Sabine River from River from north-north->south>south
Storms Storms train over train over the same the same areasareas
Low cuts Low cuts off over off over west TXwest TX
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7 AM
Tuesday AM
Thru
Tuesday PM
Model Radar
Simulation
10 AM
1 PM
4 PM
Note kinks in line
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Rainfall Forecast Rainfall Forecast Tuesday AM – WednesdayAMTuesday AM – WednesdayAM
Axis of heavy Axis of heavy rains along rains along LA/TX LA/TX border and border and SW ARSW AR
3”- 3”- 6” ..isolated 6” ..isolated 8”8”
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SPC Slight risk areaSPC Slight risk area
Severe Weather Threat – TuesdaySevere Weather Threat – Tuesday
Primary Threats:Primary Threats:1.1.Damaging WindsDamaging Winds2.2.TornadoesTornadoes
Increased Risk in Orange outlined areasIncreased Risk in Orange outlined areas
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Wednesday PMWednesday PM Heavy Heavy
Band shifts Band shifts into into Eastern LAEastern LA
Low still Low still cutoff over cutoff over TXTX
Rainfall Rainfall over in TX. over in TX. Ongoing in Ongoing in LA, S AR.LA, S AR.
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Rainfall Forecast Rainfall Forecast Wednesday AM – Thursday AMWednesday AM – Thursday AM
Heaviest axis Heaviest axis expected expected across across Eastern LA.. Eastern LA.. US 165 US 165 CorridorCorridor
2”- 3” …2”- 3” …isolated 4”isolated 4”
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Computer Model Total Rainfall Computer Model Total Rainfall Forecast Forecast (ECMWF)(ECMWF)
Note the heavy axis in East TXNote the heavy axis in East TXSW AR/ SE OKSW AR/ SE OK
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Computer Model Total Rainfall Computer Model Total Rainfall Forecast Forecast (GFS)(GFS)
2 Swaths of 2 Swaths of 5”-8” 5”-8”
This model This model has shown has shown the highest the highest amounts amounts through the through the forecastforecast
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Computer Model Total Rainfall Computer Model Total Rainfall Forecast Forecast (NAM)(NAM)
1 large 1 large Swath of Swath of 5”-8” with 5”-8” with a max of a max of 9”-10”9”-10”
This model This model has been has been the the Western Western mostmost
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Computer Model Total Rainfall Computer Model Total Rainfall Forecast Forecast (NAM)(NAM)
1 large 1 large Swaths of Swaths of 5”-8” with a 5”-8” with a max of 9”-max of 9”-10”10”
This model This model has been has been the Western the Western mostmost
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Computer Model Total Rainfall Computer Model Total Rainfall Forecast Forecast (SREF)(SREF)
1 large 1 large Swath of Swath of 5”-8”5”-8”
This is a This is a combinatiocombination of n of numerous numerous model runsmodel runs
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Some perspective on the Some perspective on the amountsamounts
Top 10 Wettest March – SHV Top 10 Wettest March – SHV (1874-2011)(1874-2011)Rank Value Rank Value
Ending Date Ending Date 1. 11.99 3/31/1945 2. 11.67 3/31/1876 3. 9.93 3/31/1912 4. 9.31 3/31/1922 5. 9.30 3/31/1934 6. 9.27 3/31/1874 7. 9.00 3/31/1888 8. 8.72 3/31/1997 9. 8.04 3/31/1894 10. 7.90 3/31/2000
*** We could break the top 10 wettest
MarchRainfalls this
week!!
Month to date:3.41” – SHV6.68” – LFK6.42” – MLU3.03” – TYR3.03” – TXK2.43” - DEQ
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Precipitable Water (inches)Precipitable Water (inches)A measure of the amount of moisture in the A measure of the amount of moisture in the
atmosphereatmosphere
Max 1.77”Max 1.80”
7 AM Tues Wed AM
Forecasts from the GFS computer model
GFS model Indicating 85 kt low level jet
Believability?
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Climatology of Climatology of Precipitable WaterPrecipitable Water
X
This event falls above the 99th percentile and approaches the maximum value observed in March….based on the forecast PW values
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Impacts
National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana
River ImpactsRiver Impacts Sabine, Neches, Sulphur, Red Sabine, Neches, Sulphur, Red
system..including parts of the Red, Upper system..including parts of the Red, Upper OuachitaOuachita
Moderate flooding most areas…Some Major Moderate flooding most areas…Some Major (Sulphur)(Sulphur)
Depends on location of heaviest rainfall & Depends on location of heaviest rainfall & duration at which the rain fallsduration at which the rain falls
Other ImpactsOther Impacts Significant Flash Flooding Significant Flash Flooding
Tues AM->Thu AMTues AM->Thu AM Severe Weather Threat Severe Weather Threat
Late Mon/Early TuesLate Mon/Early Tues Damaging Winds - StrongDamaging Winds - Strong TornadoesTornadoes
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NEXT CONFERENCE CALL:
Possibly Friday 3/20 Time Possibly Friday 3/20 Time TBDTBD
www.srh.noaa.gov/shv/www.srh.noaa.gov/shv/briefingbriefing
National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana