Subj : HVYSNOW: Probabilistic Heavy Snow And Icing Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Feb 21 2024 19:25:10 FOUS11 KWBC 211925 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 224 PM EST Wed Feb 21 2024 Valid 00Z Thu Feb 22 2024 - 00Z Sun Feb 25 2024 ....Central Rockies... Day 1... A shortwave trough traversing the Four Corners region this afternoon will direct a plume of 500-700mb moisture over the Central Rockies that results in periods of heavy snow in elevations >9,000ft in the Colorado and southern Wyoming Rockies. Snow will pick up in intensity through the afternoon and into the overnight hours. Snow will stick around into the day on Thursday thanks to lingering upslope flow out of the N-NW thanks to high pressure over the Tetons. Snow eventually tapers off by Thursday evening as upslope flow weakens and mid-level moisture exits to the east. Latest WPC PWPF shows moderate-to-high chances (50-80%) for snowfall totals >6" at elevations >9,000ft which include the Park Range of northern Colorado and Ferris Mountains of southern Wyoming. The WSSI shows Minor Impacts are possible in these areas through Thursday. ....Northern Pennsylvania & Maine... Day 3... The same shortwave trough responsible for snow across portions of the Intermountain West on Wednesday will race east into the mid-Mississippi Valley and spawn a wave of low pressure over the Lower Great Lakes. Strong 850-700mb WAA and 290K isentropic glide over the Northeast Thursday night fosters a precipitation shield that will overrun a sufficiently cold air-mass to support snow over parts of interior Northeast Thursday and into Thursday night. In northern Pennsylvania and even as far south as the Laurel Highlands, an opportunity for an icy wintry mix will present itself Thursday into Thursday evening. WPC PWPF shows low chances (10-20%) for >0.1" of ice accumulations in north-central PA on Thursday that may contribute to slick roads in some isolated areas. While some minor snow/ice accumulations are possible as far south as the Catskills, Berkshires, Green, and White Mountains, most probabilistic guidance is keying in on northern Maine as the favorite to witness heavy snow Thursday night. The wildcard in this setup is the formation of a coastal low over the Gulf of Maine that, depending on track, could lead to a deformation axis of heavy snow from central Maine to Downeast Maine between midday Friday and Friday evening. At the moment, WPC PWPF shows low chances (10-30%) for snowfall totals >4" across northern Maine. These totals coincide with the Probabilistic WSSI (WSSI-P) which depicts low chances (10-30%) for Minor Impacts across northern Maine on Friday. 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .