Subj : Major Winter Storm Today To : All From : Dumas Walker Date : Mon Dec 29 2025 09:02 am FOUS11 KWBC 290718 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 218 AM EST Mon Dec 29 2025 Valid 12Z Mon Dec 29 2025 - 12Z Thu Jan 01 2026 *** Major Winter Storm for the Upper Midwest/Great Lakes and Northeast Transitions to Lake-Effect Snow Today *** ....Great Lakes/Northeast... Days 1-3... Maximum impact level from WSSI: Major to locally Extreme Mature cyclone with a central pressure in the mid 970s mb this morning will be near peak intensity, with direct affects lessening through the day. Comma-head/TROWAL snows over Michigan will transition to lake-effect snow by this afternoon as the parent low continues through Ontario into Quebec. In its wake, winds will still be strong, creating blowing and drifting snow even where none may be falling. Blizzard warnings remain in effect over parts of the Upper Midwest this morning and will continue over the U.P. of Michigan through the day. An additional 8 inches of snow after 12Z is likely (>50% probability) over at least the eastern half of the U.P. With cyclonic flow around the low continuing today, the lake effect machine will kick in downwind of Lake Michigan (this morning) and Erie/Ontario later this afternoon/evening. An additional shortwave will fly in from Canada through the Great Lakes TUesday afternoon into Wednesday, adding a little more lift to the region. Westerly to WNW flow into the central Appalachians will also promote modest snows for eastern WV, western MD, and into the Laurel Highlands. With the strong flow over the lakes, some multi-lake connection could support long-lived streamers well inland. Yet another shortwave out of Canada later Wednesday into Thursday will help maintain the lake effect off Erie/Ontario through the end of this forecast period. Three-day total snowfall will be highest in NW PA and in the Chautauqua Ridge as well as into central NY near Syracuse and into the Tug Hill Plateau. Winds will sometimes be transient and sometimes rather stationary, and totals may vary widely on a given day. WPC probabilities for at least 8 inches of snow through 12Z Thursday are >50% over western Lower Michigan, northeastern OH into southwestern NY, over the central Appalachians, and into central NY to the Tug Hill. Within these regions, WPC probabilities for at least 18 inches of snow are >50% over NW PA and SW NY and near Syracuse toward Watertown (Oswego, Pulaski, etc.). In the Northeast, the advancing warm front then cold front will flush out the entrapped cold surface air which has resulted in significant freezing rain accumulations so far. A little more icing of a tenth or so is possible just after 12Z before a quick changeover to rain then back to snow post-FROPA. ....Southeast New Mexico/Guadalupe Mountains... Day 1... Maximum impact level from WSSI: Moderate A cold front plunging southward has brought in much colder temperatures to the region. ENE sfc flow behind it beneath moisture advecting eastward from the Pacific will lead to snow over the Guadalupe and southern Sacramento Mountains Monday. With 700mb WAA via SWrly flow over southern NM and west TX colliding with northerly 700mb winds over the High Plains, mid-level FGEN could support some modest snow especially over the terrain. WPC probabilities of at least 4 inches of snow are >50% in the mountains, with lighter accumulations eastward to the TX border. ....Sierra Nevada... Day 3... Incoming moisture from the Pacific will reach the central and southern Sierra Wednesday into Thursday morning. Snow levels are quite high -- 9000 to 10,000ft -- and accumulations will be light even at the highest elevations. Fracasso ....Winter Storm Key Messages are in effect. Please see current Key Messages below... https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png $$ --- SBBSecho 3.28-Linux * Origin: Capitol City Online (21:1/175) .