Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 508 PM EST Wed Feb 01 2023 Valid 00Z Thu Feb 02 2023 - 00Z Sun Feb 05 2023 ...Significant ice storm from the Southern Plains through the Mid-South into Thursday... ...West-Central Texas through the Mid-South... Day 1... Positively-tilted upper trough (weakly-closed upper low) over northern Mexico this evening will push eastward through Texas tonight through Thursday. Broad southwest to southerly flow above the surface will continue to bring >0C temperatures aloft to the region atop a mostly sub-freezing boundary layer, anchored by a ~1030mb high centered over the Red River Valley. This has allowed a steady supply of colder and drier air to funnel in on a north to northeast wind which has maintained the freezing rain event over the area, with some sleet and a narrow band of snow on the far northwest side of the precip shield. As the upper trough moves to the east on D1, the moisture source (driven by strong but now weakening IVT out of the east Pacific) will push eastward across the Lower MS Valley into the Southeast, gradually bringing the wintry precip to an end into the start of D2. CAM guidance showed a slight southward/colder trend toward more freezing rain along the AR/LA border but otherwise still focused the main axis from central TX arcing to the northeast and east across central/southern AR with a broad area of >0.10" icing. WPC probabilities of at least 0.25" ice accretion are >10-30% in this area, with a much larger area of probabilities of at least 0.10" ice (>70%). ...Great Lakes... Day 1-3... Lake effect snow D1 will persist over the Keweenaw Peninsula and into the Tug Hill where several inches of snow are likely through Thursday. During the day tomorrow, a strong arctic front rounding the southwest side of a deep/cold upper low over Hudson Bay will bring a brief but very cold shot of air (T850 < -20C around the Great Lakes but closer to -40C in the core of the cold) to the Great Lakes/Northeast into D2. Broad area of light snow (with some embedded snow squalls) driven by the front will kick off a somewhat short-lived lake effect event Friday. Though temperatures in the column will be colder than the DGZ, strong UVV on NW flow will yield several inches of snow on NW winds into Friday before heights rise and surface high pressure moves through the area. Lighter snow on warm advection will skirt the Upper Lakes into upstate New York D3. WPC probabilities of at least 4 inches of snow are high (>70%) in favored areas of the U.P., northwestern Lower Michigan, and into the Tug Hill and Chautauqua Ridge in NY. ...Northwest... Days 2-3... On D2, upper low over the northeast Pacific will lift northeastward and weaken into British Columbia, bringing a wave of precipitation into the Northwest. Southerly to southwesterly flow will bring in milder air but the moisture plume should focus on the coastal ranges and NorCal ranges as the front comes through and weakens/dissipates. By D3, shortwave will push out of the NW followed by weak ridging ahead of the next Pacific trough that will bring in another wave of snow to at least the Olympics by late Friday. Focus late D2 into early D3 will be over the WA Cascades where more than 6 inches are likely above 5000-6000ft. Fracasso ...Key Messages for Jan 30-Feb 2 Southern Plains to Mid-South Ice Storm... --Freezing rain, mixing with sleet at times, is expected to continue into Thursday. --Additional ice accumulations of a quarter to half an inch are forecast over much of western, central, and northern 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 into Thursday AM. Travel conditions will improve by Thursday afternoon. --Prolonged power outages and further tree damage are expected.