Subj : HVYSNOW: Probabilistic Heavy Snow And Icing Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Mar 23 2025 18:06:56 FOUS11 KWBC 231806 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 206 PM EDT Sun Mar 23 2025 Valid 12Z Sun Mar 23 2025 - 12Z Wed Mar 26 2025 ....Pacific/Interior Northwest to Northern Rockies... Day 1... Ongoing Atmospheric River moving onshore western Washington this afternoon will continue to spread moisture across the Northwest, far northern Great Basin and into the northern Rockies through Monday. Snow levels across the WA Cascades will start out this evening above 6000 ft and remain between 6000 to 8000 ft throughout the remainder of the event (above major mountain passes). Snow levels across the Great Basin and northern Rockies will also continue to rise above 7000 ft during the D1 period as residual moisture on the southern edge of the AR reaches into the western/northern WY ranges. WPC probabilities for at least 6 inches of snow are medium (30-50%) and are confined to the northern WA Cascades and highest ranges of MT and WY (above 7000 to 8000 ft). Precipitation cuts off by D2 as anomalous upper ridging builds across the western U.S. as the next system approaching the region cuts off over the northeast Pacific. Snell ....Upper Midwest/Great Lakes/Northeast... Days 1-3... The winter storm has kicked off in the Upper Midwest with the storm strengthening this afternoon as it tracks towards the Upper Great Lakes tonight. The deformation zone is pivoting beneath the TROWAL over northern Minnesota. There is also heavy snow unfolding in northern Wisconsin where strong 850-700mb FGEN and WAA aloft is paired with dynamic cooling aloft to produce >1"/hr snowfall rates in some cases. By this evening, the storm will begin its weakening phase with most snow coming via WAA over the eastern Michigan U.P. and northern most portion of Michigan's Mitten. Farther west, CAA on the back side of the low will generate lake-enhanced snowfall from the Minnesota Arrowhead on east to northern Wisconsin and as far east as the Keweenaw Peninsula of Michigan's U.P.. Look for periods of snow lake-effect snow to linger through Monday across the Michigan U.P. and northern lower Michigan. WPC probabilities show moderate-to-high chances (50-70%) for additional snowfall amounts >4" for the areas referenced above, with some localized areas seeing additional snowfall amounts up to 8", especially in the Michigan U.P.. Farther east, the storm's warm front will advance east into the Northeast tonight with low-level WAA and 290K isentropic ascent aloft. The antecedent air-mass is initially cold enough to support snow in the as far south as the Poconos and Catskills, but the best chance for accumulating snowfall will take place over the Adirondacks, Green, and White Mountains tonight and into Monday morning. Some minor ice accumulations are possible in parts of the northern Mid-Atlantic tonight and into early Monday morning. A wave of low pressure will attempt to develop near Downeast Maine Monday and could wrap some Atlantic moisture around its northern and western flank. This would allow for some minor snow accumulations to unfold from central to eastern Maine through Monday evening. WPC probabilities do highlight low- to- moderate chances (20-50%) for some targeted areas of >4" snowfall totals in parts of the Adirondacks, Green Mountains, White Mountains, and east-central Maine. As the storm departs Monday night, some lake effect streamers off Lakes Erie and Ontario should lead to minor snowfall totals in northwest Pennsylvania, western NY, and northern New York. The area most likely to see measurable snowfall is the Tug Hill where the primary band off Lake Ontario and the Tug Hill's elevation provide a more favorable setup for accumulating snowfall. WPC probabilities shows low chances (10-30%) for 48-hour snowfall totals >8" in the Tug Hill, showing there is the potential for some localized amounts that could be on the heavier side through Tuesday. Some minor snow accumulations are possible as far south as the Central Appalachians but totals most totals staying in the coating-3" range. For days 1-3, the probability of significant icing of at least 0.10" is less than 10 percent across the CONUS. Mullinax $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .