Sierra Nevada and Intermountain West Snow Outlook, Oct 31–Nov 1, 2026

Outlook

The damage map keeps National Weather Service snow and ice reports for the Sierra Nevada and the Intermountain West, inside the stored search area. Reno, Sacramento–Stockton–Modesto, Salt Lake City, Boise, and Grand Junction–Montrose are tracked markets in that area, along with the other airports inside the box. The dates run Saturday, October 31, through Sunday, November 1. The Weather Prediction Center probabilistic heavy snow and icing discussion on this page is the latest stored product, replaced on each collect. National Weather Service and model snowfall at the scored airports is not graded yet, because no snowfall amount from those sources is stored for this storm.

Damage map

Winter weather discussion

Weather Prediction Center probabilistic heavy snow and icing discussion, 239 AM EDT Fri Oct 30 2026. Valid 12Z Fri Oct 30 2026 - 12Z Mon Nov 02 2026. A newer discussion replaces this quote on the next collect when it still names this region.

Valid 12Z Fri Oct 30 2026 - 12Z Mon Nov 02 2026 ...Sierra Nevada into the Intermountain West & Four Corners... Days 1-3... An impressive full-latitude upper trough, represented by NAEFS height anomalies falling below the 10th percentile along most of the Pacific Coast, will gradually pivot eastward into early next week over the Intermountain West and Rockies. Downstream of this deepening trough, a subtropical jet streak will amplify and surge northeast, with downstream diffluence overlapping with intensifying mid-level divergence to produce robust deep layer ascent across the Southwest and Intermountain West this weekend. Moisture embedded within a pronounced IVT plume (peak IVT above 500 kg/m/s from the West-WRF centered over the Southwest) will lift into the increasing ascent, resulting in widespread precipitation, most prominent on D2 and D3, from southern CA through the Northern Rockies. The WAA accompanying the IVT will push snow levels to 9000-10000 ft across the Intermountain West (slightly lower-8000 ft in ID/MT and higher-11000 ft in CO), keeping most of the precipitation rain. However, accumulating snow is likely in the higher elevations, with periodic lowering of snow levels to 7000-9000 ft (near the NBM 10th percentile, varying with location) thanks to steep lapse rates aloft and some enhanced ascent through 700-600mb fgen and upslope forcing. As the pronounced trough crosses over the Rockies by the end of D3, snow levels will gradually fall below 7000-8000ft across the Northern Rockies and Great Basin, but coinciding with drying northwesterly mid-upper- level flow early Monday. Some light snow is possible D1, but in general accumulating snow will occur primarily on D2 and D3. During this time, the higher elevations of the Sierra will be favored for the heaviest accumulation, with a 60% chance of at least 12 inches, with local maxima approaching 2 feet. Additional heavy snow exceeding 6 inches is likely (>60%) across the higher elevations of the Sawtooth of ID, the Uintas of UT, Wind River Range of WY, and the San Juans of CO, where locally 12+" is possible. All of this snow will likely be comprised of less- than-climatological SLR, leading to substantial snow load impacts (50-90% chances of at least moderate impacts due to snow load from the WSSI-P across the San Juans).

Snowfall at scored stations

National Weather Service and model snowfall is not graded yet for the scored stations. No snowfall amount from those sources is stored for this storm.