Bulletin d’avalanche

Stevens Pass

Northwest Avalanche Center
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Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Triggering a large avalanche in wind drifted snow still remains a concern in upper elevation terrain steeper than 35 degrees. Use visual clues to identify and avoid wind loaded slopes, and seek out lower-angled and wind-sheltered terrain to reduce your risk. An active weather pattern will resume Tuesday night, bringing rising avalanche danger. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Recently formed slabs of wind drifted snow will continue to be reactive in the right location with a human trigger. Cohesive slabs rest over the most recent (12/21) melt-freeze crust, which may act as a good sliding surface for avalanches. Look for shooting cracks and strong over weak layering as you assess areas of wind drifted snow. Use test slopes to check how well recent slabs are bonding before venturing into bigger terrain. Avoid wind loaded slopes greater than 35 degrees if you find signs of instability or fresh avalanches. Slabs will be deeper and wider in higher elevation terrain and near ridgelines. When in doubt, seek out wind-sheltered slopes and terrain less than 35 degrees.  

    Example photo of a wind slab running on a crust.

Avalanche Discussion

About 6-8in of new snow accumulated in the Stevens Pass zone since Christmas. Southwest winds were strong during the storm, and observers reported intense wind transport in exposed locations over the past few days. There is uncertainty about how the new snow is bonding to existing surfaces in upper elevation terrain.  Previous snow surfaces consisted of this slick crust, surface hoar, near-surface facets, and wind broken particles. In windward locations, the recent crust could still make for some slick and challenging travel. 

The last deep persistent slabs occurred over a week ago, and recent observations in the area indicate this layer is now unreactive to triggers. In isolated areas, you may still find weak snow deeper in the snowpack, but very large and destructive avalanches on this layer are unlikely. Additionally, the stout crust formed on 12/21 appears to be stabilizing the lower snowpack, and the weak layers associated with the widespread natural avalanche cycle last week are moist and gaining strength. 

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.

Régions couvertes