Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

A major winter storm will impact the Snoqualmie Pass area Sunday night and Monday. Expect very dangerous avalanche conditions with large natural avalanches, particularly at mid and upper elevations. This isn’t a time to try and thread the needle. Stay off of and out from under all steep open slopes.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1.5–2.5

    Monday’s avalanche danger isn’t worth overthinking. Very strong and gusty winds, heavy precipitation, and fluctuating snow levels check all the boxes to create very dangerous avalanche conditions at mid and upper elevations. While you will likely be able to trigger a slide on any slope that isn’t scoured down to the old crust, they will be much deeper and more deadly in areas where the wind piles the snow deeper. We even expect several rounds of natural avalanches due to prolonged windy conditions and continued snowfall. For that reason, avoid traveling in areas where avalanches can start, run, and stop. 

    At lower elevations, it will take a bit before enough snow accumulates to begin to build an avalanche issue. However, with such strong wind speeds, this will likely occur in openings where the snow can drift into deeper slabs. Even in the trees, watch for textured surfaces and firmer drifts to identify steep slopes you want to avoid.

    (3/17/2022)

    Example: A large natural avalanche in wind-loaded terrain from earlier this season.

    Photo: Dallas Glass

Avalanche Discussion

After what feels like months of rather benign weather, a major winter storm will impact Snoqualmie Pass Sunday night through Tuesday morning. High snowlevels for the first part of the storm should maintain rain well above Pass level until after the cold front passes sometime Monday morning. With a significant amount of water expected before the precipitation turns to snow, you could encounter wet avalanches at lower elevations. The most dangerous of these would be glide avalanches or large blocks of snow shedding from rocky areas. Just because there, isn’t much new snow on the ground first thing Monday morning, don’t let these potential overhead hazards slip your mind. 

At mid and upper elevations the new snow will accumulate on two common surfaces, a firm melt-freeze crust or softer recent storm snow (with the same crust underneath). In both instances, the bonding of the old and new snow may change dramatically with elevations. While the Early April Crust could allow avalanches to run quickly, it should also prevent slides from involving older snow below.

Régions couvertes