Avalanche forecast

Olympics

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
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Out of date — this forecast expired 6 years ago.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

We maintain uncertainty surrounding interfaces 3 ft down in the snowpack that could produce a very large avalanche. Any slabs avalanche you trigger in the new snow, cornice, or even a human could all trigger this low-likelihood, high consequence problem.  Choose slopes less than 35 degrees if you venture onto larger terrain features.

Avalanche problems

  • Wind Slabs

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

    You are likely to trigger a small wind slab near ridgelines and in above treeline terrain. Focus on the snow that drifts on the slopes since the end of the day on Thursday where you might find a shallow temperature crust up to 5000 ft or so. Several inches of fresh snow with moderate to occasionally strong westerly winds will load lee slopes. While the wind forecast has been for consistent W winds, winds on Hurricane Ridge have been and may continue to come from a variety of directions. Check the direction of fresh sharp cornices and wind lips, rime plastered on trees, and snow stripped from trees. Steer around recently wind-loaded terrain features near treeline and avoid all slopes steeper than 35 degrees above treeline.

    Example of wind-affected snow below corniced ridgelines where you are more likely to trigger a wind slab avalanche. Photo: Ethan Taylor

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Persistent slab avalanches are still on our minds and they should be on yours. The primary layer of concern involves facets above a crust about 35 inches below the surface. About 2-3 inches above that interface, there is a layer of surface hoar. Persistent slabs are notoriously slow to heal, propagate widely, and these are still within the range of human trigger. They can also be triggered by cornice collapse or a wind slab avalanche.  Any avalanche on either weak layer will be large to very large and difficult to survive. Although snowpack test results were not impressive, similar layers of rounding facets and surface hoar in the Cascades have produced numerous avalanches, some of them human-triggered. Given our uncertainty surrounding this layer, we suggest continuing to dial back your terrain selection. Reduce your exposure to avalanche terrain steeper than 35 degrees.

    (2/4/2021) Persistent slab avalanche that likely failed naturally during the storm (around 2/1). Hurricane Ridge Road in the foreground. Photo: Sam Luthy.

Avalanche Discussion

NWAC and NPS professionals reported 35 inches of "right-side-up" or increasing density snow above the decomposing 1/13 rain crust.  Near-surface facets above the 1/13 crust and surface hoar several inches above that are showing signs of rounding. These layers are becoming a low likelihood, high consequence threat. The observers noted an impressive avalanche cycle from the January 31 - Feb 2 storm cycle.  Crowns were particularly prevalent on NE aspects where almost every steep, convex rollover produced an avalanche. Some aspects could still be close to the tipping point, but just waiting for a trigger. This uncertainty warrants increased caution and a greater margin for safety on Friday.

2020-21 Forecast Schedule: Avalanche danger ratings will be issued for the Olympics every Friday through Sunday and during mid-week holidays. During the week when the Hurricane Ridge road is closed, forecast information will be updated daily to include expected conditions and relevant travel advice under the No Rating label.

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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