Island Park

Near Island Park and West Yellowstone danger will rise through the day as heavy snowfall and wind-drifted snow add weight to a snowpack with weak layers buried 1-3 feet deep. Natural and human triggered avalanches large enough to bury a person are likely later today. Avalanches can be triggered from flatter terrain below steep slopes. The safest choice is to travel on slopes less than 30 degrees steep, and stay off of flatter terrain below steep slopes.

Near Cooke City, Island Park and West Yellowstone we issued an avalanche warning, and very dangerous conditions will develop through the day and overnight. Heavy snowfall and wind-drifted snow will add weight to a snowpack with buried weak layers. Natural and human triggered avalanches are likely. Avalanches can be triggered from flatter terrain below steep slopes. 

Near Cooke city weak layers are buried 3-5 feet deep. The snowpack has already been stressed by several feet of snow and wind-loading over the past week, and may be close to breaking and causing large to very large avalanches. Near Island Park and West Yellowstone weak layers are buried 1-3 feet deep and natural and human triggered avalanches large enough to bury a person are likely later today. The safest choice is to travel on slopes less than 30 degrees steep, and avoid crossing or hanging out below steep slopes. Avalanche danger is HIGH near Cooke City, Island Park and West Yellowstone.

Near Bozeman and Big Sky, new snowfall today will make human triggered avalanches likely. Less snow is expected than elsewhere and it should start later, but amounts and timing are uncertain, so significant hazards might develop in the middle of the day. Avalanches can involve drifts of the snow that falls today, or larger persistent slab avalanches can break wider and deeper on buried weak layers. See our recent videos and observations for more info on the snowpack and distribution of persistent weak layers. 

Be cautious of slopes steeper than 30 degrees. Either avoid them or carefully assess the snowpack and consequences of a slide before entering avalanche terrain. Avalanche danger will rise to CONSIDERABLE at upper and middle elevations in the Bridger Range, Gallatin Range and Madison Range.