special winter weather briefing 2/3/2011 slides: keith stellman national weather service...

Special Special Winter Weather Winter Weather

BriefingBriefing2/3/20112/3/2011slides:slides:

www.srh.noaa.gov/shv/briefingwww.srh.noaa.gov/shv/briefingKeith 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

HH

Current Radar/Temps Current Radar/Temps – 8 AM– 8 AM

Snow/Sleet

•1” in Mansfield LA

• Some melt/refreeze occurring

Reason for the earlier Reason for the earlier onsetonset

Models Models underestimatinunderestimating winds at g winds at 700mb700mb

Palestine and Palestine and Winnfield wind Winnfield wind profiler show profiler show 30-35 kts of 30-35 kts of wind at 10000ftwind at 10000ft

Models show Models show 20-25 kts20-25 kts

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

Temperature profile at Midnight- Lufkin Temperature profile at Midnight- Lufkin

Free

zing

line

High Res High Res models models suggest all suggest all snow East snow East Texas - Texas - LufkinLufkin

Very Very SaturatedSaturated… … moderate moderate to heavy to heavy snowsnow

Height

Surface Tempeatures 25-28

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 Jena (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

Model Forecast Noon Model Forecast Noon TodayToday

Snow to Sleet/Freezing Rain Line

• Models Models waver on waver on the mix the mix line. line.

• Blue Blue barbs barbs indicate indicate south south winds winds transporttransporting ing moisture moisture northnorth

Model Forecast 6 PM Model Forecast 6 PM TodayToday

Snow to Sleet/Freezing Rain Line

• Models Models waver on waver on the mix the mix line. line.

• Blue Blue barbs barbs indicate indicate south south winds winds transporttransporting ing moisture moisture northnorth

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

High Res ModelHigh Res Model This model This model

has has consistently consistently shown a shown a swath of swath of precip precip across the across the northwestnorthwest

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

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

Model Concensus (SREF)Model Concensus (SREF) This blend This blend

shows the shows the highest swath highest swath in the in the Southeast and Southeast and south (0.50-south (0.50-1.00”) 1.00”)

Sabine, Sabine, Natchitoches, Natchitoches, Grant, Winn, Grant, Winn, La Salle, La Salle, CaldwellCaldwell

The 2” lineThe 2” line

Rouge Rouge estimate of the estimate of the mix linemix 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

Winter Storm Winter Storm Warning/Advisory (6 pm Warning/Advisory (6 pm this evening through 6 this evening through 6

pm Fridaypm Friday Winter Winter Precipitation Precipitation expected expected across the across the entire Four entire Four State Region. State Region.

Warning areas Warning areas in blue. in blue.

Advisory areas Advisory areas in purple.in purple.

Temperatures Temperatures Thursday Night - FridayThursday Night - Friday

Lows Highs

ImpactsImpacts 1-3 inches snow/minor 1-3 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>ShrevepTyler>Longview>Shreveport>Magnolia>El Dorado ort>Magnolia>El Dorado and points south.and points south. Will re-evaluate Will re-evaluate

amounts/warnings this amounts/warnings this afternoonafternoon

Lower visibilitiesLower visibilities

Ground temps ~40/35 in Ground temps ~40/35 in AR…precip will stick to AR…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>Natchi>Nacogdoches>Natchitoches-toches->Winnfield>Monroe>C>Winnfield>Monroe>Columbia>Colfax>Jenaolumbia>Colfax>Jena

Over 0.50” would Over 0.50” would cause widespread cause widespread Power outagesPower outages

Instant freeze on all Instant freeze on all surfaces with temps in surfaces with temps in the 20sthe 20s

NEXT CONFERENCE CALL:

Thursday (today) 4 PM Thursday (today) 4 PM www.srh.noaa.gov/shv/briewww.srh.noaa.gov/shv/brie

fingfing

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana