Winter storm snow forecast: heavy mountain totals in the Rockies, slick commutes from Mid-Atlantic to Northeast

A new surge of winter weather is underway today (Saturday, December 6), with heavy mountain snow piling up across the northern Rockies and the Intermountain West while a weaker wave delivers light snow and pockets of icing from the Mid-Atlantic into parts of the Northeast. The combination will snarl travel on high passes out West and produce scattered slick spots on busy corridors back East. Forecast details may evolve through the day as bands wobble; check local alerts if you’re in an affected area.

Winter storm snow forecast: where the heaviest falls

• Northern Rockies & Intermountain West: A moisture plume and persistent upslope flow are producing the most significant accumulations. Mountain zones in Idaho, western Montana, northwest Wyoming and high terrain of Utah and Colorado are favored for 6–24 inches through late Saturday into Sunday, with locally higher drifts where winds funnel along ridgelines. Valleys and lower elevations will see lighter totals or a wintry mix, especially where temperatures hover near freezing. Whiteout conditions are possible at times on exposed passes.

• Pacific Northwest interior: Cascades and Blue Mountains pick up steady mountain snow with lighter amounts east of the crest. Travel will be slow on higher summits; chains and traction tires may be required during heavier bursts.

• High Plains fringe (MT/WY/CO): Snow spreads into adjacent plains in bands, with several inches possible where persistent orographic bands set up. Gusty winds on the open prairies could briefly reduce visibility.

Light snow and ice for the Mid-Atlantic into the Northeast

A separate, fast-moving disturbance brought a coating of snow to parts of the Mid-Atlantic early today, with pockets of freezing drizzle or light freezing rain near tidal zones and along stretches of the I-95 corridor. As the wave exits, precipitation diminishes from southwest to northeast, but spotty slick patches can linger on untreated roads, bridges and overpasses through the morning where surface temperatures remain below freezing. Farther north into interior New Jersey, eastern Pennsylvania and southern New England, a light glaze or dusting may lead to uneven conditions neighborhood-to-neighborhood.

Timing the storm

• West (local time):

  • This morning–tonight: Heaviest snow focuses on western Montana and central/northern Idaho, expanding into the Tetons and the Wasatch. Mountain corridors like I-90 (Lookout Pass) and US-2/Marias Pass face prolonged impacts.

  • Tonight–Sunday: Snow intensity shifts south/east through the central Rockies. High passes on I-70 (CO/UT), US-550 (San Juans) and WY-22 (Teton Pass) face intermittent closures or chain controls.

  • Sunday night: Gradual tapering for many ranges, but lingering upslope may keep light snow going on favored west- and north-facing slopes.

• East (ET):

  • Early morning today: Light snow and a thin glaze mixed in spots across portions of MD/PA/NJ; scattered slick spots on secondary roads.

  • Late morning–afternoon: Precipitation winds down, clouds break from southwest to northeast, and temperatures slowly edge upward limiting additional accumulation.

Schedule subject to change with band placement and local microclimates.

Travel impacts and preparedness

• Roads: Expect rapidly changing conditions crossing elevation. A mile of vertical rise can mean a flip from wet pavement to deep snow. Carry chains where required, keep the tank at least half full and pack winter essentials (warm layers, food, water, scraper, phone power).

• Airports: Intermittent delays are possible at mountain hubs when de-icing surges or visibility drops. Minor flow-through delays may pop up in the Northeast during morning push periods due to de-icing and runway treatments.

• Power/trees: Wind-buffeted ridgelines may see tree limb breaks in the West. East of the Appalachians, any icing remains spotty and light; widespread power issues are not expected but isolated outages can’t be ruled out.

How this pattern is setting up the week ahead

Behind the western storm, colder air spills southeastward while the jet stream remains active. That keeps mountain snow chances elevated into early next week, with occasional light snow or mixed episodes sneaking onto the adjacent plains. In the East, the quick-hitting wave exits and a brief lull arrives before the next clipper or coastal disturbance eyes the region. Confidence is highest for continued frequent, terrain-driven snow in the Rockies; confidence is lower for exact timing/track of the next Eastern system, which hinges on how fast energy transfers near the coast. Recent updates indicate additional advisories are likely to be issued in favored western ranges; details may evolve.

Quick look: expected snow ranges

*Ranges reflect the most likely outcomes; localized bands can over- or under-perform.

• West: Plan for significant mountain snow and deteriorating pass travel from this morning into Sunday. Delay non-essential mountain crossings when heavy bands set up.

• East: Expect minor, nuisance-level wintry precip early today with improving conditions this afternoon; watch for black ice tonight where skies clear and temps dip back below freezing.

Stay alert to local advisories and real-time updates where you live, especially if your route crosses higher terrain or known lake-effect or upslope hotspots.