Subj : Major Winter Storm tonigh To : All From : Dumas Walker Date : Sun Dec 28 2025 09:05 am FOUS11 KWBC 280724 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 224 AM EST Sun Dec 28 2025 Valid 12Z Sun Dec 28 2025 - 12Z Wed Dec 31 2025 *** Major Winter Storm for the Upper Midwest/Great Lakes tonight then into the Northeast Monday *** ....Great Lakes/Northeast... Days 1-3... Maximum impact level from WSSI: Major to locally Extreme A vigorous closed low along the Montana/North Dakota border this morning will dig southeastward into Iowa this evening as the upper jet punches northeastward into the western Great Lakes. This will set the stage for a rapidly-deepening/bombing cyclone the will move across Lower Michigan tonight then into Canada on Monday. The storm will have three main facets: synoptic snow via comma- head/lake-enhancement from MN to the U.P. of Michigan, freezing rain to its east (PA/Northeast US) in advance of a surface warm front, and lake- effect snow as the system departs across all Great Lakes. Snow associated with the approaching cold front from the west will merge into the developing comma-head snowfall to the northwest of the sfc low over MN/northern WI this afternoon along an inverted surface trough and on the edge of the moisture gradient to the southeast (where PW anomalies in the warm sector rise to >99th percentile). Snow will expand and increase in intensity over northern WI/U.P. of MI this evening, quickly becoming enhanced by Lake Superior as cyclonic flow rapidly intensifies. Just east/ahead of the low center will be a wintry mix over the northern L.P. and eastern U.P. of Michigan with sleet and freezing rain eventually giving over to snow early Monday. The low pressure will continue to deepen and briefly slow over Lake Huron early Monday as the system becomes vertically stacked and occludes (awaiting the mid-level low from the west). Peak intensity should be reached Monday morning (mid 970s mb central pressure) over Lake Huron or Georgian Bay with the warm conveyor belt now completed wrapped up and around the low. Snowfall will maximize over the northern shore of the U.P. where powerful onshore flow pivots as the low passes. Locally, 1-2ft of snow is likely over much of the U.P. D1-2 probabilities of at least 6 inches of snow are >50% from south central MN eastward across the northern 1/2 of WI and the northern 1/4 of Lower Michigan northward across all of the U.P., where probabilities of at least 12 inches are >70%. Probabilities for at least 24 inches of snow are >20% over much of the northern and eastern U.P. Well ahead of the main surface low, warm air advection will overrun cold <32F surface temperatures from central PA this afternoon through the Northeast tonight. Given snow is on the ground through much of the region, the WAA aloft will have a tough time reaching the surface, especially in normally sheltered locations. Without a surface high to the north, temperatures will have an easier time rising due to the freezing rain process itself, but again counteracted by snow-covered ground which could act to keep the surface warm front farther south. However, with such a strong southerly flood of warm air, most guidance does show at least a brief changeover to rain for nearly all of the Northeast except for northern New England. Where the cold air holds on the longest, ice could accumulate enough to be hazardous to trees and/or power lines. WPC probabilities for at least 0.25" icing are >50% over the Adirondacks and across much of central VT/NH into southwestern Maine. In addition, probabilities for at least 0.50" icing are 20-50% in these regions. Across northern Maine, the column may be stay entirely below freezing near the Canadian border as a triple point low may help prevent a southerly wind component. WPC probabilities for at least 4 inches of snow are >30% over far northern Maine. As the low moves through Ontario into Quebec, strong westerlies will favor lake-effect snow across all Great Lakes, but focused downwind of Lakes Michigan, Erie, and Ontario. Some multi-lake connection and variable wind directions could support long-lived single bands far inland away from the lake shores in concert with breezy/windy conditions (i.e., blowing and drifting snow). In addition, upslope flow into the central Appalachians will favor some snow into the Laurel Highlands southward to eastern WV. WPC probabilities for at least 8 inches of snow are >50% over northeast Ohio and NW PA into the Chautauqua Ridge and south towns of Buffalo as well as over central NYS around Syracuse northward to Watertown and the Tug Hill Plateau. Some areas could see more than 12 inches of snow where bands maintain some residence time (>50% chance). ....Southeast New Mexico/Guadalupe Mountains... Day 2... Maximum impact level from WSSI: Moderate A cold front racing southward from the CO Rockies today will leave behind a sfc-700mb baroclinic zone along the Rio Grande as moisture from the Pacific will be directed eastward across northern Mexico. Temperatures may be just cold enough even to the valley floors for snow to accumulate, aided by an onset time early Monday D2 with precipitation continuing through Monday night. Topographic enhancement on the Guadalupe and southern Sacramento Mountains will result in the highest probabilities for at least 4 inches of snow -- generally 40-60%. To the east, light snow of a couple inches is possible to the TX border where WPC probabilities of at least 2 inches are 20-50%. Fracasso/Jackson ....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) .