The snowpack and its associated avalanche problems are highly variable by aspect and elevation, with wet-snow avalanches in south-facing terrain and persistent slab avalanches potentially failing on buried weak layers in high-elevation, north-facing terrain. The simple version is to get in and out of avalanche terrain before the thin surface crust breaks down and becomes wet, and either avoid steep north-facing slopes at upper elevations or dig and test for instability before committing to steep terrain in these areas where the snowpack remains mostly dry.
Read the full forecast for more details about the complexities of today’s avalanche conditions.
Wet loose avalanches may be a few inches deep as surface crusts melt through the day. If surface crusts fully melt, wet-loose avalanches could gouge deeper into the saturated, wet snowpack below, and wet slab avalanches will also be possible.
Persistent slab avalanches are most likely on high elevation, shady slopes where the snowpack stayed drier during last week's heat.
The weather this last week is rapidly pushing the mountain snowpack through a spring transition. The snowpack and its associated avalanche problems vary widely by aspect and elevation. Given this variability, consistently reevaluate and adapt accordingly to evolving avalanche problems as you move from one area to the next and as temperatures rise throughout the day.
Wet snow problems: Temperatures overnight were 5-10 degrees F warmer than the night before, generally remaining above freezing. This will not do our snowpack any favors as temperatures climb well into the 40s to mid-50s F today. With clear skies overnight, snow surfaces mostly froze, but crusts will be thin and will break down earlier than yesterday. Increasing clouds and winds this afternoon will slow melting, making wet loose avalanches the primary problem, but as the snow warms, these can entrain significant snow volume, and more destructive wet slab avalanches are a potential (Cedar Mt. 1, Cedar Mtn. 2, Woody Ridge, Town Hill, North Bridger Range).
Thankfully, decreasing stability is relatively easy to recognize, and travel advice is simple. Get in and out of the mountains early in the day while surface crusts are intact. Sinking into wet or slushy snow more than a few inches deep is evidence that the snowpack is moving toward instability and signals the need to head home, get off and out from under slopes steeper than 30 degrees, or move to shadier, north-facing terrain. An unsupportable snowpack indicates an increasing likelihood of more dangerous wet snow avalanches.
Cornice fall is an additional temperature-related hazard, as above-freezing temperatures weaken these large overhanging masses of snow. While in the Emigrant Peak basin yesterday (outside our forecast area), we talked with a group that mentioned a crack opening up 30 feet behind a monstrous cornice, yikes! Minimize your time below large cornices.
Dry snow avalanches: It is hard to believe that there are slopes out there with dry snow, but a natural persistent slab avalanche ran in the Bridger Range within the week (details and photos), and Saturday’s skier-triggered persistent slab avalanche near Emigrant Peak (outside the forecast area) failed on weak, faceted snow that formed in January (observation). The Emigrant Peak avalanche broke nearly 1000’ wide and 1-3 feet deep. Similar slides remain possible within the boundaries of our forecast regions on middle- and upper-elevation, northerly-facing slopes. Testing the top three feet of the snowpack with an extended column test will give you more information about potential instability.
Avalanche danger is MODERATE throughout the forecast area.
