Cooke City

Watch out if winds pick up today, drifting recent snow. Either way, large Persistent Slab avalanches remain possible, as well as smaller, thinner Wind Slabs. Look for signs of instability and back off steep slopes if you find them. 

Avalanche conditions are dangerous in the mountains around Bozeman and Big Sky. Thursday’s storm put down 1-2 ft of new snow that is being drifted by moderate-strong winds and is sitting above persistent weak layers on many slopes. We got many reports of avalanches yesterday, both human triggered and slides that broke naturally during the storm (observation, observation, observation).  With winds picking up today, it’ll be just as easy to trigger an avalanche on a wind loaded slope today as it was yesterday, if not more so. Strong winds are getting down to lower elevations than usual, so be on the lookout for drifts, even far below ridgelines. Non-windloaded slopes, without persistent weak layers, should be stabilizing - the problem is, most slopes have weak layers of some sort in the upper snowpack. These persistent weak layers were already unstable before the storm and can be triggered from below (observation). Human triggered avalanches are likely and the avalanche danger is CONSIDERABLE. Avoiding riding on or passing directly beneath all steep slopes is the simplest way to stay safe today. 

The mountains around West Yellowstone, Island Park, and Cooke City only got a couple inches of snow out of this storm, so avalanches are less likely, but still possible, with windloaded slopes being the most problematic. Today’s increasing winds are supposed to stay further north, but if they come further south than expected, fresh wind drifts could be easily triggered. Persistent weak layers are widespread. We haven’t seen avalanches on them in the last few days (the last one being Monday in S. Madison Range), but there have been signs that it’s still possible (Lionhead shooting crack). Keep an eye out for wind drifting and watch for signs of instability, such as cracking or collapsing, and back off steep slopes if you find them. If you don’t see any other signs of instability, dig down and test the weak layers buried 2-3 ft deep as a final check before getting onto steep slopes. There were many dry-loose avalanches around Cooke City yesterday (observation), they’ll be less likely today, but could be a hazard in steep, technical terrain. The avalanche danger is MODERATE in these areas.