Lionhead Area

There is still a lingering possibility of triggering a large Persistent Slab avalanche on weak layers near the ground.  If you were going to trigger one of these slides, I expect it’d be up near a ridgeline in a thin area near rocks. Also, keep an eye out for isolated pockets of unstable wind drifted snow, particularly in extreme or high consequence terrain where a small slide would have big consequences.

The avalanche danger is LOW across much of the advisory area today. The exception is upper elevations in the mountains near West Yellowstone, where the danger remains MODERATE.

It’s been a week since the last substantial snowfall and three days since the last dusting of snow (around Bozeman and Big Sky) on Tuesday afternoon. Strong winds have drifted all the soft snow that was available to be drifted and warm temperatures have glued on almost all of those drifts at this point. Still, keep an eye out for isolated pockets of unstable wind drifted snow, particularly in extreme or high consequence terrain where a little Wind Slab avalanche would have big consequences. 

Persistent Slab concerns are lingering in the mountains around West Yellowstone. Without recent loading, the likelihood has gone way down, but the possibility of triggering a deep slide is still there. If one of these slides breaks, it’d break near the ground and be a really big avalanche. The last Persistent Slab avalanches were a week ago in the Lionhead area (observation) and in late December in the Southern Madison Range (observation, observation). If you were going to trigger one of these slides, I expect it’d be up near a ridgeline in a thin area near rocks. Unfortunately, digging and doing snowpack tests isn’t going to give you much information about the likelihood of triggering a Persistent Slab avalanche on any particular slope. If you’re going to ride on steep, upper elevation slopes in these areas, you need to accept the slight, but non-zero, possibility of triggering a big slide. 

This is the time to fall back on the standard avalanche precautions - ride one at a time on steep slopes, have a partner watching you from a safe spot, and make sure everyone in your group is carrying a beacon, shovel, and probe.