Northern Gallatin Range

Strong winds the last couple days formed widespread drifts that create the main avalanche concerns today. On wind-loaded slopes a person can trigger wind slab avalanches of recently drifted snow, and larger persistent slab avalanches could break deeper and wider. If you seek out steep terrain, avoid recently wind-loaded slopes, and dig down a couple feet to look for and assess buried weak layers.

Near Island Park and West Yellowstone large avalanches remain likely for a person to trigger. Over the last 10 days there were eight human-triggered avalanches, and five of those caught and buried snowmobilers (avalanche observations). Avalanches have been breaking 2 feet deep on weak layers that were buried by snowfall over the last two weeks. A few days have passed without new snow, but recent strong winds drifted snow into thicker slabs to further stress buried weak layers. The best strategy to avoid a large persistent slab avalanche is to avoid riding on and underneath slopes steeper than 30 degrees, especially slopes that were recently wind-loaded. Avalanche danger is CONSIDERABLE near Island Park and West Yellowstone.

In the Northern MadisonandNorthern Gallatin Ranges and near Cooke City, strong winds the last couple days formed widespread drifts that create the main avalanche concerns today. On wind-loaded slopes a person can trigger wind slab avalanches of recently drifted snow, and larger persistent slab avalanches could break deeper and wider (Cooke City video). There are few slopes left unaffected by wind, but slopes sheltered from the wind also have potential for an avalanche to break 1-2 feet deep on buried weak layers. If you seek out steep terrain, avoid recently wind-loaded slopes, and dig down a couple feet to look for and assess buried weak layers. Avalanche danger is MODERATE in Cooke City and the Northern Madison and Northern Gallatin Ranges.

In the Bridger Range avalanches are unlikely and avalanche danger is LOW. This range received the least recent snowfall in our forecast area. The 3” of snow that fell on Tuesday was drifted into wind slabs which were generally small and have had time to stabilize. Stay alert for a drift or two that might remain unstable, especially in terrain where even a small slide would have large consequences, like above cliffs, trees or other terrain traps. There are also weak layers buried up to a foot deep, but we have not seen evidence they have enough snow above them to be a problem yet (observation, observation). If you plan to ride steep terrain it won’t hurt to dig down a couple feet and check for weak layers or unstable wind slabs.

WET SNOW

Increasing clouds and temperatures similar to yesterday will probably inhibit wet snow avalanche activity. However, if today is warmer and sunnier, stay alert for wet loose avalanches if you find moist or wet snow surfaces. These are most likely on steep, sunny slopes and often initiate near exposed rocks or cliffs.