1. Special Winter Weather Briefing 2/3/2011 slides: www.srh.noaa.gov/shv/briefing Keith Stellman National Weather Service Shreveport, Louisiana

2. Overview Tonight/Friday Tonight/Friday Arctic air in place across the region Arctic air in place across the region Upper level system moves in and draws moisture in from the gulf over the cold air. Upper level system moves in and draws moisture in from the gulf over the cold air. Accumulations of 1-3 inches snow/minor sleet accumulations possible I-20 Corridor and south (Winter Weather Advisory area) Tyler>Longview>Shreveport>Magnolia>El Dorado and points south. Accumulations of 1-3 inches snow/minor sleet accumulations possible I-20 Corridor and south (Winter Weather Advisory area) Tyler>Longview>Shreveport>Magnolia>El Dorado and points south. Ice accumulations of 0.25-0.50 inches possible…(Winter Storm Warning area) Lufkin->Nacogdoches>Natchitoches- >Winnfield>Monroe>Columbia>Colfax>Jena Ice accumulations of 0.25-0.50 inches possible…(Winter Storm Warning area) Lufkin->Nacogdoches>Natchitoches- >Winnfield>Monroe>Columbia>Colfax>Jena Beginning this evening 6 pm ending by 6 pm Friday. (Winter precipitation north of the Winter Storm Warning area may begin a little later than 6 pm this evening.) Beginning this evening 6 pm ending by 6 pm Friday. (Winter precipitation north of the Winter Storm Warning area may begin a little later than 6 pm this evening.) National Weather Service Shreveport, Louisiana

3. Big Picture National Weather Service Shreveport, Louisiana Today Tngt Friday Strong Upper Level Low Pressure Area H

4. Current Radar/Temps – 8 AM Snow/Sleet 1” in Mansfield LA Some melt/refreeze occurring

5. Reason for the earlier onset Models underestimating winds at 700mb Models underestimating winds at 700mb Palestine and Winnfield wind profiler show 30- 35 kts of wind at 10000ft Palestine and Winnfield wind profiler show 30- 35 kts of wind at 10000ft Models show 20- 25 kts Models show 20- 25 kts

6. Sleet/snow/Freezing rain Dilemma Temperature profile at Midnight- Lufkin Freezing line High Res models suggest all snow East Texas - Lufkin High Res models suggest all snow East Texas - Lufkin Very Saturated… moderate to heavy snow Very Saturated… moderate to heavy snow Height Surface Tempeatures 25-28

7. Sleet/snow/Freezing rain Dilemma Temperature profile at Midnight- Jena Freezing line High Res models suggest Freezing Rain in Jena (Southeast) High Res models suggest Freezing Rain in Jena (Southeast) Cold nose helps rain freeze quickly Cold nose helps rain freeze quickly Height Surface Tempeatures 28-32

8. Sleet/snow/Freezing rain Dilemma Temperature profile at Midnight- Monroe Freezing line High Res models suggest Mix with more Freezing Rain High Res models suggest Mix with more Freezing Rain Warm nose not as prevalent but deep enough to melt the snow into sleet/FZRA Warm nose not as prevalent but deep enough to melt the snow into sleet/FZRA Height Surface Tempeatures 27-30

9. Sleet/snow/Freezing rain Dilemma Temperature profile at Midnight- Natchitoches Freezing line Warm Nose appears and looks deep enough to melt the snow Warm Nose appears and looks deep enough to melt the snow Could either be sleet or freezing rain Could either be sleet or freezing rain Toledo Bend- >Natchitoche s->Jonesboro Toledo Bend- >Natchitoche s->Jonesboro Height Surface Tempeatures 28-31

10. Model Forecast Noon Today Snow to Sleet/Freezing Rain Line Models waver on the mix line. Models waver on the mix line. Blue barbs indicate south winds transporting moisture north Blue barbs indicate south winds transporting moisture north

11. Model Forecast 6 PM Today Snow to Sleet/Freezing Rain Line Models waver on the mix line. Models waver on the mix line. Blue barbs indicate south winds transporting moisture north Blue barbs indicate south winds transporting moisture north

12. Total Liquid Equivalent (precip amounts) High Res Model This model has consistently shown a swath of precip across the northwest This model has consistently shown a swath of precip across the northwest Generally > 0.25” of precip in Deep East TX, all of LA. Generally > 0.25” of precip in Deep East TX, all of LA.

13. Total Liquid Equivalent (precip amounts) Model Concensus (SREF) This blend shows the highest swath in the Southeast and south (0.50-1.00”) This blend shows the highest swath in the Southeast and south (0.50-1.00”) Sabine, Natchitoches, Grant, Winn, La Salle, Caldwell Sabine, Natchitoches, Grant, Winn, La Salle, Caldwell The 2” line The 2” line Rouge estimate of the mix line Rouge estimate of the mix line

14. Timing 3PM-6PM 6PM-9PM Midnight - 3 AM Heaviest starts occurring After 9 PM -> 6AM 3 AM – 6 AM 6 AM – 9 AM Light snow late morning tapering Off by ~noon

15. Winter Storm Warning/Advisory (6 pm this evening through 6 pm Friday Winter Precipitation expected across the entire Four State Region. Winter Precipitation expected across the entire Four State Region. Warning areas in blue. Warning areas in blue. Advisory areas in purple. Advisory areas in purple.

16. Temperatures Thursday Night - Friday LowsHighs

17. Impacts 1-3 inches snow/minor sleet accumulations possible I-20 Corridor and south (Winter Weather Advisory area) Tyler>Longview>Shreveport>M agnolia>El Dorado and points south. 1-3 inches snow/minor sleet accumulations possible I-20 Corridor and south (Winter Weather Advisory area) Tyler>Longview>Shreveport>M agnolia>El Dorado and points south. Will re-evaluate amounts/warnings this afternoon Will re-evaluate amounts/warnings this afternoon Lower visibilities Lower visibilities Ground temps ~40/35 in AR…precip will stick to bridges/overpasses and main roadways Ground temps ~40/35 in AR…precip will stick to bridges/overpasses and main roadways Cold temperatures through Saturday AM to keep it around Cold temperatures through Saturday AM to keep it around Ice accumulations of 0.25- 0.50 inches possible) Lufkin- >Nacogdoches>Natchitoc hes- >Winnfield>Monroe>Colu mbia>Colfax>Jena Ice accumulations of 0.25- 0.50 inches possible) Lufkin- >Nacogdoches>Natchitoc hes- >Winnfield>Monroe>Colu mbia>Colfax>Jena Over 0.50” would cause widespread Power outages Over 0.50” would cause widespread Power outages Instant freeze on all surfaces with temps in the 20s Instant freeze on all surfaces with temps in the 20s

18. NEXT CONFERENCE CALL: Thursday (today) 4 PM www.srh.noaa.gov/shv/briefing Thursday (today) 4 PM www.srh.noaa.gov/shv/briefing National Weather Service Shreveport, Louisiana