Bridger Range

Instability is limited to a few small, isolated drifts and wet loose avalanches that start at a point and entrain snow as they move downhill. Recreating in terrain free of terrain traps like cliffs, gullies, and rocks will go a long way toward making a day in the mountains easy and safe. Evaluating for isolated instability in the upper 2 feet of the snowpack and watching for wet snow avalanches if snow surfaces become saturated will get you the rest of the way there.

Today’s forecast is dedicated to the memory of Ben Richards. Ben was killed in an avalanche near Big Sky 19 years ago today.

Persistent slab avalanches breaking up to 2 feet deep are the primary concern. While problematic weak layers formed throughout the advisory area, instability and recent avalanche activity are concentrated in the Island Park, West Yellowstone, and Cooke City areas, which picked up the most snow over the last couple of weeks. Small, wet loose avalanches are a secondary concern if snow surfaces become saturated in south-facing terrain.

Yesterday in the Lionhead area, we observed conditions less sensitive than when Ian was there last week, but unstable test results and two recent cornice-triggered slides were clear evidence that if you hit the wrong spot, the snow will avalanche (Ian’s observation, yesterday’s observation). Skiers in the nearby Southern Madison Range intentionally triggered an avalanche that failed a couple of feet deep on the buried weak layer on a small test slope (details). And, this weekend, Alex found 6 recent avalanches in Cooke City (observation). This adds to a large catalogue of avalanches in the last two weeks (activity).

In the Southern Madison and Southern Gallatin Ranges, and the Island Park, Lionhead, and Cooke City areas, the danger is MODERATE. Weak layers are likely present, so terrain selection rather than snowpack assessment is the best tool for safe travel. If you elect to travel on slopes steeper than 30 degrees, choose smaller terrain in the lower-angle range of the spectrum with clean runouts free of terrain traps like cliffs, trees, and confined gullies.

In the Northern Madison and Northern Gallatin Ranges, recent snowfall totals have been lower with correspondingly fewer avalanches. Persistent slab avalanches are possible, but it seems that the extra weight of recently wind-drifted snow is necessary to push weak layers over the edge. A slide on Buck Ridge last Friday is a good example (details and photos). This weekend, a group in Beehive Basin noted that half of their tests yielded unstable results (observation).

In the Northern Madison and Northern Gallatin Ranges, the danger is MODERATE at mid- and upper-elevations. Dig and test for instability in the upper 3 feet of the snowpack, and favor wind-sheltered terrain where slides are less likely.

There has been little recent snow in the Bridger Range, and avalanches are unlikely. Buried weak layers exist, but they are not unstable (observation, observation). Instability is limited to a few small, isolated drifts and wet loose avalanches that start at a point and entrain snow as they move downhill. Neither of these instabilities will be dangerous without terrain traps such as trees, rocks, and cliffs, which can amplify the consequences of the avalanche. The danger in the Bridger Range is LOW.