Special Special Winter Weather Winter Weather

BriefingBriefing2/3/2011 – 4 PM2/3/2011 – 4 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 Tonight/FridayTonight/Friday

Arctic air in place across the regionArctic air in place across the region Upper level system moves in and draws moisture in Upper level system moves in and draws moisture in

from the gulf over the cold air.from the gulf over the cold air. Accumulations of 1-3 inches snow/minor sleet Accumulations of 1-3 inches snow/minor sleet

accumulations possible I-20 Corridor and south accumulations possible I-20 Corridor and south (Winter Weather Advisory area) (Winter Weather Advisory area) Tyler>Longview>Shreveport>Magnolia>El Dorado Tyler>Longview>Shreveport>Magnolia>El Dorado and points south. and points south.

Ice accumulations of 0.25-0.50 inches possible…Ice accumulations of 0.25-0.50 inches possible…(Winter Storm Warning area) Lufkin-(Winter Storm Warning area) Lufkin->Nacogdoches>Natchitoches->Nacogdoches>Natchitoches->Winnfield>Monroe>Columbia>Colfax>Jena>Winnfield>Monroe>Columbia>Colfax>Jena

Beginning this evening 6 pm ending by 6 pm Friday. Beginning this evening 6 pm ending by 6 pm Friday. (Winter precipitation north of the Winter Storm (Winter precipitation north of the Winter Storm Warning area may begin a little later than 6 pm this Warning area may begin a little later than 6 pm this evening.) evening.)

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

Big PictureBig Picture

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

TodaTodayy

TngtTngt

FridFridayay

Strong Upper Level

Low Pressure Area

HHArctic Surface

High

Current Radar/Temps – 3:15 Current Radar/Temps – 3:15 PMPM

Initial precip band

moving north

Temps still at or below Freezing

Sleet/snow/Freezing rain Sleet/snow/Freezing rain DilemmaDilemma

Temperature profile at Midnight- Jena Temperature profile at Midnight- Jena

Free

zing

line

High Res High Res models models suggest suggest Freezing Freezing Rain in Rain in Jena with Jena with warm nose warm nose at 1000-at 1000-5000 ft 5000 ft (Southeast(Southeast))

Cold nose Cold nose helps rain helps rain freeze freeze quicklyquickly

Height

Surface Tempeatures 28-32

Sleet/snow/Freezing rain Sleet/snow/Freezing rain DilemmaDilemma

Temperature profile at Midnight- MonroeTemperature profile at Midnight- Monroe

Free

zing

line

High Res High Res models models suggest suggest Mix with Mix with more more Freezing Freezing Rain Rain

Warm Warm nose not nose not as as prevalent prevalent but deep but deep enough to enough to melt the melt the snow into snow into sleet/FZRAsleet/FZRA

Height

Surface Tempeatures 27-30

Sleet/snow/Freezing rain Sleet/snow/Freezing rain DilemmaDilemma

Temperature profile at Midnight- Temperature profile at Midnight- NatchitochesNatchitoches

Free

zing

line

Warm Warm Nose Nose appears appears and looks and looks deep deep enough to enough to melt the melt the snowsnow

Could Could either be either be sleet or sleet or freezing freezing rainrain

Toledo Toledo Bend-Bend->Natchito>Natchitoches-ches->Jonesbor>Jonesboroo

Height

Surface Tempeatures 28-31

Total Liquid Equivalent (precip Total Liquid Equivalent (precip amounts) amounts)

18Z High Res Model Run18Z High Res Model Run

Model has Model has backed off a backed off a bit on total bit on total amountsamounts

Generally > Generally > 0.25” of 0.25” of precip in precip in Deep East Deep East TX, all of TX, all of LA except LA except NW.NW.

Total Liquid Equivalent (precip Total Liquid Equivalent (precip amounts) amounts)

Model Concensus (SREF)Model Concensus (SREF)

Model has Model has reduced reduced amounts amounts slightly as slightly as well (0.50 is well (0.50 is a max across a max across the the Southeast)Southeast)

The 2” lineThe 2” line

Rouge Rouge estimate of estimate of the mix linethe mix line

TimingTiming3PM-6PM 6PM-9PM Midnight - 3 AM

Heaviest starts occurringAfter 9 PM -> 6AM

3 AM – 6 AM 6 AM – 9 AM

Light snow late morning taperingOff by ~noon

Temperatures Temperatures Thursday Night - FridayThursday Night - Friday

Lows Highs

ImpactsImpacts 1-2 inches snow/minor 1-2 inches snow/minor sleet accumulations sleet accumulations possible I-20 Corridor and possible I-20 Corridor and south (Winter Weather south (Winter Weather Advisory area) Advisory area) Tyler>Longview>ShrevepoTyler>Longview>Shreveport>Magnolia>El Dorado rt>Magnolia>El Dorado and points south.and points south.

Isolated 3” amounts Isolated 3” amounts possible further south and possible further south and east.east.

Lower visibilities after Lower visibilities after MidnightMidnight

Ground temps ~40/35 in Ground temps ~40/35 in AR… AR… Precip will stick to Precip will stick to bridges/overpasses and bridges/overpasses and main roadwaysmain roadways

Cold temperatures Cold temperatures through Saturday AM through Saturday AM to keep it aroundto keep it around

Ice accumulations of Ice accumulations of 0.25-0.50 inches 0.25-0.50 inches possible) Lufkin-possible) Lufkin->Nacogdoches>Natch>Nacogdoches>Natchitoches-itoches->Winnfield>Monroe>>Winnfield>Monroe>Columbia>Colfax>JenColumbia>Colfax>Jenaa

Over 0.50” would Over 0.50” would cause widespread cause widespread Power outagesPower outages Only isolated areas in Only isolated areas in

extreme Southeastextreme Southeast Instant freeze on all Instant freeze on all

surfaces with temps surfaces with temps in the 20sin the 20s

NEXT CONFERENCE CALL:

Next Thursday @ 10 AM Next Thursday @ 10 AM www.srh.noaa.gov/shv/briewww.srh.noaa.gov/shv/brie

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National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana