Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
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Out of date — this forecast expired 6 years ago.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

Very windy conditions and a few inches of new snow will form slabs that you may trigger. If you see fresh cornices or find smooth pillow-like drifts use caution. Even small avalanches can harm you if they push you over a cliff or bury you in a gully.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Very strong easterly winds Tuesday night should form fresh slabs on lee sides of exposed features at any elevation. Because of the direction of this wind event, you will likely find the majority of wind deposited snow on SW-N-NE aspects. In some locations, they may develop over a weak snow interface causing slabs to trigger easily, propagate widely, and run quickly. With the potential for very touchy avalanches on some unusual aspects and at lower elevations, it’s safe to say these may not be your “run-of-the-mill” Snoqualmie wind slabs. Use visual clues such as small sharp cornices and smooth pillow-like drifts to identify wind-loaded features. Even though we think these potential avalanches should remain small, they can still harm you in high consequence terrain.

    (12/22/2020) Example: A small wind slab in a confined terrain feature. Similar slides are possible Wednesday.

Avalanche Discussion

Snoqualmie Pass should receive a few more inches of very low-density snow by mid-day Wednesday. This will add to a series of small storms that continue to slowly grow the upper snowpack. On open slopes, you could find 6-10” (15-25cm) of snow over a very prominent and sometimes icy crust (1/13). Very weak snow grains may hide within this recent snow. On Saturday (1/23) facets, surface hoar, and a very thin sun crust were observed and possibly buried around the zone. Now 4-6” of snow covers this potentially weak interface. Without a slab, no avalanche activity has occurred on this layer. As more snow falls and the winds begin to blow that may change. 

Outside of wind-affected areas, expect unconsolidated snow poorly bonded to a very firm crust. You may trigger small loose dry or sluff avalanches on slopes greater than 40 degrees. Don’t let these slides catch you off guard if you travel in higher consequence terrain such as above an open creek or cliff. 

While travel conditions continue to improve with the new snow, you may still encounter icy slopes. Expect frim conditions beneath thick trees and along wind-scoured ridgelines. This observation from Tuesday highlights these potential challenges. 

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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