Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 231 PM EDT Sun Apr 27 2025 Valid 00Z Mon Apr 28 2025 - 00Z Thurs May 1 2025 ...Great Basin and Northern Rockies... Days 1-2... An upper low traversing the Great Basin today will be responsible for periods of higher elevation snow through the northern Nevada ranges this afternoon and evening. Snow levels will be as low as 6,000ft in some cases, but the heavier amounts are likely to resume above 7,000ft. As the upper low weakens and moves east tonight, mountains snow will ensue within the more remote reaches of the Wasatch and Uinta of Utah, while minor amounts are possible as far east as the peaks of the Colorado Rockies through Monday morning. Additional snowfall accumulations of 2-6" are forecast in the >6,000ft ridge lines of northern Nevada through early Monday morning. The ranges most likely to see the heaviest snowfall will be in the Absaroka, the Tetons, and the Big Horns. These ranges will reside favorably beneath the the best PVA at 250-500mb and a pivoting axis of >90th climatological percentile 500-700mb moisture content aloft. 850-700mb winds will back of out of the NE-E as the upper low slides south of these ranges and a surface cold front passes through tonight. While the cold front does provide a brief infection of CAA aloft, the cold air source is not sufficient enough to produce much more than minor snowfall accumulations below 7,000ft. The heaviest amounts will be confined to elevations at/above 8,000ft in the ranges listed above, with some locally heavier amounts as low as 7,000ft in the Big Horns. Snow tapers off by Monday afternoon and evening as the upper low races east towards the Northern Plains Monday evening. WPC probabilities highlight high chances (>70%) for snowfall totals >12" in the Absaroka above 7,000ft with some totals in the Absaroka-Beartooth Wilderness seeing totals above 24 inches in some cases above 9,000ft. WPC probabilities show moderate-to-high chances (50-70%) for snowfall totals >12" in the Big Horns above 7,000ft, while similar chances for >6" of snow exist in the Tetons above 8,000ft. The probability of at least 0.10" of freezing rain across CONUS is less than 10%. Mullinax