Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 358 AM EST Wed Feb 01 2023 Valid 12Z Wed Feb 01 2023 - 12Z Sat Feb 04 2023 ...Significant and long-duration ice storm from the Southern Plains through the Mid-South into Thursday... ...West-Central Texas through the Mid-South... Days 1-2... c An upper low, stalled over the northern Baja at the end of highly anomalous, positively-tilted upper trough over the Southwest will continue to work in tandem with a strong upper ridge over the Gulf of Mexico to channel a plume of rich subtropical moisture into the Southern Plains and into the Mid-South. NAEFS output depicts IVT of ~500 kg/m/s over southeast TX while the available moisture aloft is from the tropical East Pacific. This stream of anomalous moisture content is embedded within strong 850-300mb mean layer winds aloft. Meanwhile, the low-levels are below freezing from the Davis Mountains of West Texas, on south to the San Antonio/Austin metro areas, through northeast TX, across Arkansas (outside of Texarkana), over northwest Miss and through central Tenn. These sub-freezing surface temperatures are reinforced by the presence of a cold high pressure ridge from the TX Panhandle east-northeast over the Middle MS Valley. The strong WAA aloft maintains warm nose aloft, causing the sleet and freezing rain that will continue through tonight and in pockets into Thursday as the focus for precip shifts east. The strong vertical ascent aloft, prolonged supply of rich atmospheric moisture, and cold air damming setup in place allows persistence of the significant ice storm. The Day 1 WPC PWPF shows the greatest probabilities (50-80%) for >0.25" of additional ice accumulation are over the Concho Valley through North Texas. Sleet will also continue to occur both in convective elements and in deeper cold layer which will generally be farther northwest in the Permian Basin into southern OK. The freezing rain and sleet will continues to cause treacherous travel conditions from TX to the Mid-South. The upper low ejects east today, crossing TX Thursday and with it an end to the warm nose and the mixed precip. Day 2 (after 12Z Thur) ice probabilities for an additional tenth inch are now 10 to 30% over southern/eastern Arkansas. ...Great Lakes... Day 1-3... Low level westerlies persist over the Lakes today with Day 1 WPC PWPF highlighting moderately-high 4"+ probabilities over the Keweenaw Peninsula in the U.P. and the Tug Hill in NY. Thursday a powerful Arctic front will race across the Great Lakes, bringing a risk for snow squalls to the U.P. Thursday afternoon and to interior NY/New England Thursday evening which can bring sudden reductions in visibility for drivers. Then lake effect snow in the following northwesterly flow comes off each lake with Day 2/2.5 probabilities for 4"+ over the eastern U.P. northwest L.P. and off the eastern half of Lake Erie. Jackson ...Key Messages for Jan 30-Feb 2 Southern Plains to Mid-South Ice Storm... --Freezing rain, mixing with sleet at times, are expected to continue into Thursday. --Additional ice accumulations of a quarter to a third of an inch are forecast over much of West, Central, and North Texas. An additional tenth to quarter inch of ice is forecast over southern Oklahoma, much of Arkansas, and east through the greater Memphis metro area. --Accumulating ice on roadways, especially bridges and overpasses, will continue to cause treacherous travel conditions. --Prolonged power outages and further tree damage are expected.