Bridger Range

Winds may increase today and create some fresh drifts. Steer around fresh drifts if you see cracking across the snow surface, especially in high consequence terrain. On sunny slopes, wet loose avalanches are possible as the recent snow gets wet and could easily slide and run long distances on crusts below. Stay off steep, sunny, high consequence slopes if you encounter a wet snow surface or if you see rollerballs or natural wet loose slides.

Today there is a wide range of avalanche danger and avalanche problems throughout the forecast area. 

Near Island Park and the Lionhead Area near West Yellowstone large persistent slab avalanches are likely. Yesterday we heard about two snowmobiler triggered avalanches that buried riders in the Centennial Range, as well as multiple other rider triggered avalanches (observation). One of these slides, on Reas Peak, partially buried two riders and fully buried two riders (observation). Over the last week these areas received 1.5-2 ft of snow equal to 1.5-2.8” Snow Water Equivalent. This snow overloaded weak layers that formed in January making it easy to trigger large avalanches which break wide and up to 2-3’ deep, and can be triggered from lower angle terrain below steep slopes. A skier triggered avalanche yesterday near Hebgen Lake is another example (observation). In the Lionhead Area and Island Park avalanche danger is CONSIDERABLE. Avoid crossing on and underneath slopes steeper than 30 degrees.

The Madison Range, Gallatin Range, and near Cooke City received less snow over the last week, but 10-15” of snow still raised the avalanche danger. Ian, Dave, and I visited these areas over the last few days and found various weak layers buried below the recent snow (Hyalite video, Beehive video, S. Madison observation, N. Gallatin video). We saw minimal signs of instability like recent persistent slab avalanches, collapsing or unstable test scores, however, we remain cautious because we have experienced being surprised by an avalanche or two breaking on surface hoar or facets. 

Despite a lack of obvious signs, there might be an unstable slab over a weak layer on a few slopes, and today’s increased wind, sun or warm temperatures may settle the recent snow into a stiffer slab that can more easily cause a persistent slab avalanche to break wide across a slope. Wind slab avalanches are an additional problem to watch for where fresh drifts are formed from today’s wind (skier triggered wind slab near Cooke yesterday, Natural wind slab). Avalanche danger is MODERATE in the Madison and Gallatin Ranges, and near Cooke City. Steer around fresh drifts, especially in high consequence terrain. Carefully assess the snowpack before riding or crossing steep slopes. Choose smaller, simpler terrain and slopes free of cliffs, trees or tight gullies which increase the consequences of a slide. 

In the Bridger Range, avalanche danger is MODERATE, and wind slab avalanches are the primary concern. Winds may increase today and create some fresh drifts. Steer around fresh drifts if you see cracking across the snow surface, especially in high consequence terrain. 

Due to near or above freezing temperatures, on sunny slopes wet loose avalanches are possible as the recent snow gets wet and could easily slide and run long distances on crusts below. Stay off steep, sunny high consequence slopes if you encounter a wet snow surface or if you see rollerballs or natural wet loose slides.