Wyoming Winter Briefing: Fog, Gusts, and Fresh Snow — Plan Your Backcountry Moves

January 03, 2026

An honest, tactical read on the week ahead for anyone heading into Wyoming’s winter wilds: the broad picture is a transient lull east of the Divide with pockets of trouble in the western valleys and another active period arriving for the high country by late Saturday night into Sunday. I’ll translate the NWS Riverton Area Forecast Discussion into clear takeaways for hikers, backcountry skiers, snowmobilers, and anyone planning long winter days outdoors.

What the forecasters saw and what it means for you

• Today into Saturday morning: Showers and light snow across parts of western Wyoming are gradually winding down. The big operational note is patchy dense valley fog lingering this morning into the afternoon in places like Star Valley and the upper Green River Basin — visibility can be as low as 1/4 to 2 miles. If you’re driving narrow mountain roads or navigating dirt approaches to trailheads, expect slow, white-knife conditions near dawn and dusk. Winter Weather Advisories that were in place have been canceled early where the heavier bands moved out.

• Mountains vs valleys: Higher ridges (Tetons, Salt River Range) still picked up the heaviest totals in the last round. The NWS expects roughly a foot or more in the Tetons/Salt River Range for the earlier storm, while other western coastal ranges saw smaller amounts. For the coming event, initial model solutions point to 6–12 inches in the western mountains Sunday–Monday, though details will evolve.

• Winds and timing: A transitory ridge is building briefly, giving milder, drier conditions east of the Divide through the weekend; however, winds increase Sunday morning along the corridor from Casper to Rock Springs. Models show strong 700-mb flow (50–60 kt) over South Pass and southern Natrona County — that translates to gusts that could periodically approach 60 mph in favored corridors. Forecasters currently expect gusts to remain mostly below high-wind warning criteria but they could be intense and sudden.

• Snow level and precipitation type: The flow looks to be south–southwest through the event. Forecast 700-mb temperatures around -4 to -6°C suggest snow levels near 5,500–6,500 ft. That means higher valleys and most mountain accesses will see snow rather than rain — and western valley floors are likely to stay cold enough for snow to accumulate.

A practical reading for outdoor recreation

• Lowland winter travel and trail access: Fog in Star Valley and the upper Green River Basin can be dense and persistent this morning; give yourself extra time to reach trailheads and expect icy spots where melt/refreeze occurs. Road crews may be dealing with scoured shoulders and drifting in wind-prone corridors by Sunday morning.

• Alpine and backcountry skiing / snowmobiling: The coming Sunday–Monday period looks like the best window for new accumulations (6–12 in in the western ranges), which is great for fresh tracks. But the same southwest wind that brings moisture also promotes wind-loading of leeward slopes. Wind slabs and scoured terrain on ridges are possible; if you’re heading into avalanche terrain, treat wind-loaded slopes with extra caution and bring the right skills and rescue gear.

• Day hikes, scramble routes, and ice climbing: East of the Divide the air will feel milder and drier this weekend — good for exposed winter hikes and approach-focused climbs where snowpack is thin. In western valleys, limited visibility and reformed cold-air inversions can keep temps low and trails slick; microspikes or crampons and trekking poles make a big difference.

• Photography and short outings: Mornings can be moody and atmospheric where fog and low clouds persist; if you want dramatic valley fog shots, aim for pre-dawn to mid-morning. If you prefer blue-sky vistas, mid- to late afternoon east of the Divide will offer the best light.

Hazards to respect

• Dense valley fog (Star Valley, upper Green River Basin): low visibility this morning and some lingering patches into afternoon.
• Gusty winds Sunday morning across the Casper–Rock Springs corridor: occasional gusts near 60 mph possible — expect whiteouts on exposed roads and open ridges.
• Wind-deposited snow: fresh wind slabs on lee slopes after the new round of snow — treat steep, wind-loaded slopes as unstable until proven otherwise.

How to plan your week

• If you want safe, scenic day trips: favor lower-elevation routes east of the Divide this weekend (less snow, more sun), and aim for midday when fog has lifted.
• If you chase fresh powder: plan for Sunday afternoon into Monday in the western ranges, but keep plans flexible and watch for updated snowfall totals and wind warnings. Consider shorter objectives and do conservative slope assessments.
• If you rely on road access through wind corridors (Casper–Rock Springs): avoid travel during the Sunday morning peak for gusts if possible.

Bottom line

A mixed week: calm and marginally milder east of the Divide with continued winter behavior out west. Small accumulations today give way to a more organized push of mountain snow late Saturday night into Sunday — compelling for powder seekers, but paired with wind and valley visibility issues that demand conservative choices. Keep an eye on updated advisories; in winter Wyoming, timing and route selection are the best risk controls.

— Your winter adventure meteorologist, translating the RIW Area Forecast Discussion into action on trailheads, ridgelines, and snowfields.