Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 448 PM EDT Fri Apr 4 2025 Valid 00Z Sat Apr 05 2025 - 00Z Tue Apr 08 2025 ...Southern Rockies and the Southern High Plains... Days 1-2... A cold front tracking south through CO this afternoon will push south through NM tonight as an upper low tracks over the southern borders of AZ/NM. Moisture ahead of this low combined with the low level cold behind the front will support heavy mountain snow on the eastern side of the southern Front Range, Sangre De Cristo and Raton Mesa through this evening before shifting south through the Sacramento Mtns Saturday morning. Upslope flow and increasing lift should enable snow rates of 1-2"/hr to work their way south later this afternoon through tonight per the 12Z HREF. 1"/hr rates also shift east over the southern High Plains of NM into the TX Panhandle. Day 1 snow probabilities for >8" are 50-80% in terrain from the Raton Mesa through the Sacramento Mtns especially including the Sangre de Cristos which have 50-70% chances for >12". Day 1 probs for >4" are 30-60% from the lower reaches of the Raton Mesa through much of eastern NM and into the Staked Plain of the western TX Panhandle south of the Pecos where snow persists into Saturday evening. ...Northern New England... Days 1/2... Expect a wintry mix from the White Mountains of NH through western Maine Saturday/Saturday night. While the airmass is not as cold as the more recent winter storm that took place earlier this week, high pressure over Quebec will provide a weak source of sub- freezing boundary layer temps. As 850-700mb WAA and 300K isentropic ascent amidst brisk SWrly flow aloft increases, a ribbon of 850-700mb areal-averaged FGEN will support a band of moderate- to- heavy precipitation that runs directly over the marginally cold air-mass in northern New England on Saturday. Precipitation may briefly start out as snow (staying all snow longest over northern Maine), but the burgeoning nose of >0C temps at low-levels will inevitably switch any snow to a sleet/freezing rain mixture from the Whites to western Maine Saturday afternoon. A weak CAD signature will linger longest along the Maine/Quebec border through Saturday night. By Sunday morning, the warm front lifts far enough north to have plain rain be the primary precipitation type. Day 1.5 WPC probabilities for ice accumulations >0.1" are 30-70% from the Whites through western Maine with 40% probs for >0.25" in the Presidential Range of the Whites. Moderate impacts from this icing are forecast in higher elevations per the WSSI. ...Michigan... Day 3... A potent reinforcing shortwave trough swings south of a cold-core low over Hudson Bay Sunday, reaching the L.P. of Michigan on Monday. PVA, low level FGEN, and Great Lakes moisture combine to produce a band of snow Sunday evening over Lake Superior that shifts south-southeast over the U.P. Sunday night and the L.P. Monday morning. Trailing cold air advection then produces some lake- enhanced snow showers behind the front. Day 3 PWPF for >6" are 10-30% across the northern L.P. Jackson