Bridger Range

Today, wet snow avalanche problems join the list alongside slides breaking within recently drifted snow and 2-3 feet deep on buried weak layers.

Dry snow instability: Steer around wind-loaded slopes where active drifting and shooting cracks can clue you in to potential instability. Test the upper 3 feet of the snowpack for instability on buried weak layers before committing to slopes steeper than 30 degrees.

Wet-snow instability: Move to shady, north-facing terrain or pack it up for the day when the upper few inches of the snowpack become moist or when roller balls and pinwheels indicate an increasing likelihood for slides.

The shift to warm temperatures and wet snow avalanches accelerates today, but before we get into that, focus on Cooke City. While the area may see some wet snow instability, temperatures will be cooler, and dry snow conditions remain quite dangerous.

When a long-time Cooke City guide sends in photos of an avalanche and mentions the debris pile “was one of the largest that I had seen in the mountains around Cooke City this winter,” I take notice (details and photos). This slide was one of many large, persistent slab and wind slab avalanches that ran in the area this weekend. Slides on Sunday alone included a remotely triggered avalanche breaking 3-4 feet deep on Republic Mountain (observations and photos), a cornice fall-triggered wind slab on Henderson (details and photos), and a slide below Henderson Bench that broke several feet deep and hundreds of feet wide (details and photos).

It just stopped snowing yesterday afternoon near Cooke City, and the danger is rated CONSIDERABLE. Conservative decision-making and cautious route-finding that generally avoids avalanche terrain is the way to stay safe. If you are considering slopes steeper than 30 degrees, select simple, less steep areas with clean runouts after evaluating the snowpack for instability and ensuring partners are safely positioned and watching.

The danger is MODERATE in the Bridger, Gallatin, Madison, Lionhead, and Island Park areas, where several hazards to watch for include wet loose, wind slab, and persistent slab avalanches, along with cornice fall as the behemoths begin to break off after a winter of growth.

Yesterday, skiers on Saddle Peak noted a large, persistent slab avalanche on the west side of the Bridger Range and triggered thin but reactive wind slab avalanches on their descent. (observations and photos). Wind slabs were mostly 2-4” deep, but one broke up to 2 feet in places. The persistent slab avalanche was similar to others that recently broke 18-36” in Jones’ Creek, Little Bear Canyon, Portal Creek, and Dudley Creek in the Bridger, Madison, and Gallatin Ranges. Test the upper 3 feet of the snowpack for instability before considering slopes steeper than 30 degrees.

Surface snow will get wet and unstable today, especially on sun-exposed southern aspects and rocky slopes. Wet loose avalanches will begin to release naturally. A larger wet slab avalanche in the Northern Gallatin Range two weeks ago is a warning sign for this week with soaring temperatures (wet-slab details). Move to shady, north-facing terrain or pack it up for the day when the upper few inches of the snowpack become moist or when roller balls and pinwheels demonstrate increasing instability. If the snowpack becomes saturated and unsupportable, it is past time to make your exit.