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Special Winter Weather Briefing 2/7/2011 – 3 PM slides: www.srh.noaa.gov/shv/briefing. Keith Stellman. National Weather Service Shreveport, Louisiana. Overview. Wednesday/Wednesday Night
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Special Winter Weather Briefing2/7/2011 – 3 PMslides:www.srh.noaa.gov/shv/briefing Keith Stellman National Weather Service Shreveport, Louisiana
Overview Wednesday/Wednesday Night Upper level trough pushes a strong cold front across the area while a surface low develops along the northern Gulf of Mexico…enhancing lift and moisture into the region. Accumulations of 4” - 6” inches in the I-30 corridor and points north. Accumulations of 2” - 4” North of I-20 to the I-30 Accumulations of 1” - 2” possible right along I-20 and ~30 miles south of I-20..could be more sleet mixed in. Snow will start in the Northwest (NE TX/SE OK) after Midnight (Wed) Sleet/snow starting in LA/South Central AR ~ 6-8 AM Wed National Weather Service Shreveport, Louisiana
Big Picture Arctic Surface High H Upper level disturbance L Today L Tuesday L Wednesday National Weather Service Shreveport, Louisiana
Current Snow Pack – 2/7/11 Snowpack extends far to the south..helping maintain arctic air
Sleet/Snow/Rain Temperature profile at 6 AM Wed (Lufkin - Mt Pleasant) • Models suggesting sleet/snow at Mt Pleasant • Warm Air below 6000 feet at LFK suggests all rain Freezing line Surface Tempeatures29-32 Surface Tempeatures36-40 Height
Sleet/snow/RainTemperature profile at NoonShreveport - Monroe • All but 1 model shows a sleet/snow mix transition to all snow by late AM/afternoon • Warm nose disappears between 6 AM - Noon Freezing line Surface Tempeatures 27-30 Surface Temps 33-36 Height
Model forecast snow amounts12Z GFS • Generally >1” along/north I-20. • 3-4”+ in I-30 corridor • The high res model is warm and shows virtually no snow. But it is only outlier attm
National Center Snow Probability • Area in Green (Moderate Risk) for 4”+ • Area in Blue (Slight Risk) for 4”+
Model ConcensusSnow Chances > 1” After 6 PM Wed Through 6 PM Wed • Probability 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 Wed
National Center Snow Forecast • Amounts have trended up and slightly south • Will be a fairly sharp line between haves/have nots >4” 2”-4 ” 1”- 2”
Temperatures Wednesday- Wednesday Night Lows Highs
Impacts • 4” - 6” inches in the I-30 corridor and points north. • 2” - 4” North of I-20 to the I-30 • 1” - 2” possible right along I-20 and ~30 miles south of I-20..could be more sleet mixed in. • Snow will start in the Northwest (NE TX/SE OK) after Midnight (Wed) • Sleet/snow starting in LA/South Central AR ~ 6-8 AM Wed • Lower visibilities • Ground temps ~45/40 in AR… • Precip will likely stick to surfaces similar to the last event…especially where the rate is higher • Cold Temps through Thu will keep it around into Friday when temps rebound into the 40s
NEXT CONFERENCE CALL: Tuesday @ 3 PM www.srh.noaa.gov/shv/briefing National Weather Service Shreveport, Louisiana