Bridger Range

It is possible for a person to trigger large avalanches breaking 1-3 feet deep on buried weak layers. Be especially cautious of steep slopes loaded by recent strong winds. Before riding or crossing any steep slopes, carefully assess the snowpack for buried weak layers. The few inches of new snow has drifted into small wind slabs. Be cautious of these thin slabs where being knocked off your feet would have large consequences.

Dangerous avalanche conditions exist near Cooke City where up to 2 feet of snow has fallen since Thursday. Yesterday, riders reported a large natural avalanche on a wind-loaded slope and several snowmobiler triggered avalanches breaking within the new snow (observation, observation). Strong winds accompanied the recent snowfall and formed thick drifts that will remain easy to trigger today. Larger persistent slab avalanches are also possible, breaking on weak layers 3-4 feet deep. Give the snowpack more time to adjust to recent heavy snow and wind-loading, and plan to avoid riding on and underneath slopes steeper than 30 degrees near Cooke City.

South of Bozeman and near Big Sky the 5-6” of snow that fell yesterday has been drifted into soft wind slabs which are easy to trigger. Prior to this snow, strong to extreme winds stripped many slopes back to old tracks and drifted snow into hard wind slabs on other slopes. These hard wind slabs are generally stubborn, but still possible to trigger and may be hidden by the new snow. Yesterday I skied in Beehive Basin and had one hard slab collapse when I kicked my boot into it (observation). Additionally, I found weak layers buried 2-3 feet deep that propagated in stability tests, reinforcing that larger persistent slab avalanches are possible. These might be more likely for a person to trigger on slopes where recently formed drifts have added more weight, but are also possible on non-wind-loaded slopes (examples of recent Persistent Slab avalanches: N. Gallatin 1, N. Gallatin 2, N. Madison). 

Avalanche danger is CONSIDERABLE in the Gallatin and Madison Ranges and near Cooke City. Either avoid avalanche terrain altogether, or carefully assess the snowpack and limit your terrain selection to smaller, non-wind-loaded slopes without terrain traps like cliffs, trees, or abrupt slope changes where debris can pile deep.

Less snow fell in the Bridger Range, Island Park, and the Lionhead area near West Yellowstone, so the avalanche danger is lower, but it remains possible to trigger a large persistent slab avalanche breaking 1-3 feet deep on buried weak layers. Ian’s video from Tuesday at Lionhead shows the poor snowpack structure that exists, and an avalanche last week in the Bridger Range is another example. The few inches of snow from yesterday has drifted into small wind slabs. Be cautious of these thin slabs where being knocked off your feet would have large consequences. Avalanche danger is MODERATE in the Lionhead area near West Yellowstone, Island Park and the Bridger Range. Carefully assess the snowpack and potential consequences of a slide before riding or crossing steep slopes.