Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Stormy weather with blowing snow and poor visibility could make it difficult to spot wind loaded slopes Saturday. Pay attention to which direction the wind transports the snow and what aspects load. If you suspect wind loading, steer around any open slope greater than 35 degrees.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    This storm looks windy. Any snow falling from the sky should easily transport and form new slabs on lee slopes and exposed features. These fresh wind deposits will rest on a variety of snow surfaces including an icy crust and weak soft snow. This may allow them to trigger easily underneath you. When winds are this strong, we often see erratic and unusual loading patterns. Don’t be surprised if you find wind slabs on a variety of aspects, well below ridgeline, and on the sides of mid-slope gullies. Poor visibility may make it difficult to rely on surface clues to help you identify wind-loaded terrain. Instead, pay attention to the wind direction and anticipate wind slabs on opposing aspects. Steer around any open slope greater than 35 degrees where you suspect wind loading. As more snow falls throughout the day, these slabs will grow larger and harder to manage. 

    In more sheltered areas, a cooling trend should create a right-side-up snowpack structure and you may see loose dry avalanches. These could run quickly if they occur over the icy crust.

    (12/25/2020) Blowing snow can help show you which aspects could harbor wind slabs. This active wind transport occurred in the Crystal backcountry on Christmas Day.

Avalanche Discussion

This storm favors the volcanoes and that’s where we expect the greatest avalanche hazard Saturday. In other locations, you could experience locally lower-danger especially if less snow falls than is forecasted. Avalanche danger should slowly increase in all locations during the day as avalanche concerns become larger and more widespread. 

Observations from the West-South over the past several days show variable snow surfaces prior to this storm. An icy crust (12/21)  formed during last weekend’s rain events and serves as the most prominent marker in the upper snowpack. In some locations, this crust is exposed due to recent winds creating very firm and slippery conditions. In other spots, 4-12” (10-30cm) of recent snow sits above the crust. You may encounter ice, breakable crust, wind deposits, and soft snow over a very short distance. Any avalanches should be limited to the snow above this recent crust. 

Even with all the snow this winter, creeks remain open at most elevations. Choose crossings carefully and give yourself extra time to navigate around these and other early season hazards. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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