Special Special Winter Weather Winter Weather

BriefingBriefing2/7/2011 – 3 PM2/7/2011 – 3 PM

slides:slides:www.srh.noaa.gov/shv/briefingwww.srh.noaa.gov/shv/briefing

Keith StellmanKeith Stellman

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

Overview Wednesday/Wednesday NightWednesday/Wednesday Night

Upper level trough pushes a strong cold front Upper level trough pushes a strong cold front across the area while a surface low develops along across the area while a surface low develops along the northern Gulf of Mexico…enhancing lift and the northern Gulf of Mexico…enhancing lift and moisture into the region.moisture into the region.

Accumulations of 4” - 6” inches in the I-30 corridor Accumulations of 4” - 6” inches in the I-30 corridor and points north.and points north.

Accumulations of 2” - 4” North of I-20 to the I-30Accumulations of 2” - 4” North of I-20 to the I-30 Accumulations of 1” - 2” possible right along I-20 Accumulations of 1” - 2” possible right along I-20

and ~30 miles south of I-20..could be more sleet and ~30 miles south of I-20..could be more sleet mixed in.mixed in.

Snow will start in the Northwest (NE TX/SE OK) Snow will start in the Northwest (NE TX/SE OK) after Midnight (Wed)after Midnight (Wed)

Sleet/snow starting in LA/South Central AR ~ 6-8 Sleet/snow starting in LA/South Central AR ~ 6-8 AM WedAM Wed

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

Big PictureBig Picture

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

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TuesdTuesdayay WednesdWednesd

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Upper level disturbance HH

Arctic Surface High

Current Snow Pack – 2/7/11Current Snow Pack – 2/7/11

Snowpack extends far to

the south..helping maintain arctic

air

Sleet/Snow/RainSleet/Snow/Rain Temperature profile at 6 AM Wed Temperature profile at 6 AM Wed

( (LufkinLufkin - - Mt PleasantMt Pleasant))

Free

zing

line

Models Models suggesting suggesting sleet/snow sleet/snow at Mt at Mt PleasantPleasant

Warm Air Warm Air below below 6000 feet 6000 feet at LFK at LFK suggests suggests all rainall rainHeight

Surface Tempeatures 29-32

Surface Tempeatures 36-40

Sleet/snow/RainSleet/snow/RainTemperature profile at NoonTemperature profile at Noon

Shreveport Shreveport - Monroe - Monroe

Free

zing

line

All but 1 All but 1 model model shows a shows a sleet/snow sleet/snow mix mix transition transition to all snow to all snow by late by late AM/afternoAM/afternoonon

Warm nose Warm nose disappears disappears between 6 between 6 AM - NoonAM - Noon

Height

Surface Tempeatures 27-30

Surface Temps 33-36

Model forecast snow amountsModel forecast snow amounts12Z GFS12Z GFS

Generally Generally >1” >1” along/north along/north I-20.I-20.

3-4”+ in I-30 3-4”+ in I-30 corridorcorridor

The high res The high res model is model is warm and warm and shows shows virtually no virtually no snow. But it snow. But it is only is only outlier attmoutlier attm

National Center Snow National Center Snow ProbabilityProbability

Area in Area in Green Green (Moderate (Moderate Risk) for Risk) for 4”+4”+

Area in Area in Blue (Slight Blue (Slight Risk) for Risk) for 4”+4”+

Model Concensus Model Concensus Snow Chances > 1”Snow Chances > 1”

Through 6 PM Wed After 6 PM Wed

Probability of >40% of 1” down to I-20 on thru 6 PM WedProbability of >40% of 1” down to I-20 on thru 6 PM Wed Probability of >40% of 1” in NE LA/SE AR after 6 PM WedProbability of >40% of 1” in NE LA/SE AR after 6 PM Wed

National Center Snow ForecastNational Center Snow Forecast

Amounts Amounts have have trended up trended up and slightly and slightly southsouth

Will be a Will be a fairly sharp fairly sharp line line between between haves/have haves/have notsnots

1”- 2”2”-4 ”>4”

Temperatures Temperatures Wednesday- Wednesday Wednesday- Wednesday

NightNight

LowsHighs

ImpactsImpacts 4” - 6” inches in the I-4” - 6” inches in the I-30 corridor and points 30 corridor and points north.north.

2” - 4” North of I-20 to 2” - 4” North of I-20 to the I-30the I-30

1” - 2” possible right 1” - 2” possible right along I-20 and ~30 along I-20 and ~30 miles south of I-miles south of I-20..could be more 20..could be more sleet mixed in.sleet mixed in.

Snow will start in the Snow will start in the Northwest (NE TX/SE Northwest (NE TX/SE OK) after Midnight OK) after Midnight (Wed)(Wed)

Sleet/snow starting in Sleet/snow starting in LA/South Central AR ~ LA/South Central AR ~ 6-8 AM Wed 6-8 AM Wed

Lower visibilitiesLower visibilities

Ground temps ~45/40 in Ground temps ~45/40 in AR… AR…

Precip will likely stick to Precip will likely stick to surfaces similar to the surfaces similar to the last event…especially last event…especially where the rate is higherwhere the rate is higher

Cold Temps through Cold Temps through Thu will keep it Thu will keep it around into Friday around into Friday when temps when temps rebound into the rebound into the 40s40s

NEXT CONFERENCE CALL:

Tuesday @ 3 PM Tuesday @ 3 PM www.srh.noaa.gov/shv/briewww.srh.noaa.gov/shv/brie

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National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana