Island Park

If you find more than 6-8” of new snow, triggering avalanches is likely on steep slopes, particularly those that have been windloaded. Where there is less new snow, conditions will be less touchy, but triggering avalanches remains possible. Avalanches could break in wind drifts or on weak layers buried a couple feet deep.

While there are many differences across the forecast area today, the contributing factors are the same everywhere - new snow and wind loading on top of weak layers in the upper snowpack. 

The mountains around Bozeman and Big Sky have a lot of new snow (10-20”) and correspondingly, have dangerous avalanche conditions and a CONSIDERABLE danger. Snowfall seems to have been very elevation dependent, so expect the deepest and most dangerous conditions at upper elevations. Wind speeds have also been right in the ideal range to drift snow. Buried weak layers are widespread in the N. Madison and N. Gallatin Ranges, and avalanches were already being triggered from a distance before this storm started (observation). In the Bridger Range we’re not as sure how widespread the weak layers are, but we know they’re out there (observation, observation), so for today, assume they’re on every slope. Additionally, the sun’s supposed to come out today - when it does, expect to see more loose snow sluffs on sunny slopes (which could be dangerous by themselves, but also make great triggers for slab avalanches) and the slab of new snow may stiffen and become even easier to trigger as a slab avalanche. Avoid riding on or directly beneath all slopes steeper than 30 degrees. Enjoy the fresh snow on low angled slopes and out in the meadows. 

I’m honestly unsure how much it has snowed in the Island Park area - the remote weather stations are giving contradictory readings. What I can tell you is that if you find more than 6-8” of new snow, triggering avalanches is likely on steep slopes, particularly those that have been windloaded. If there is less new snow, conditions will be less touchy, but triggering avalanches remains possible. The avalanche danger is rated CONSIDERABLE at mid and upper elevations today.

In the West Yellowstone and Cooke City areas, there is less new snow (2-4”) and avalanches in wind drifted areas are the primary concern. Slides on these slopes could break as thinner, smaller, Wind Slabs or on the weak layers buried a couple feet deep as wider, larger, more dangerous Persistent Slab avalanches.  Either look out for and steer clear of wind loaded slopes entirely or stop and carefully assess if you’re getting into steeper terrain. The avalanche danger is MODERATE in these areas.