Avalanche forecast

Olympics

Northwest Avalanche Center
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Avalanche danger

Tue
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Out of date — this forecast expired 6 years ago.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

New snow, wind, and warming temperatures will combine to create wind drifts you can easily trigger on Monday. Due to the ongoing threat of persistent slab avalanches, don’t get lured onto large avalanche terrain. Stick to smaller, treed slopes and lower angled features.

Avalanche problems

  • Wind Slabs

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

    Warming, winds, and moderate snowfall on Monday will build fresh slabs that you can easily trigger near and above treeline. You can trigger a slab where avalanche where you find 6" of wind-loaded snow creating a density change. A prolonged period of expected moderate winds will easily transport the existing low-density snow and slabs may load starting zones and mid-slope features alike. Note the direction of sharp, fresh cornices that overhang the wind-loaded aspects. Avoid wind-loaded slopes steeper than 35 degrees. Remind yourself that any avalanche triggered risks awakening a persistent slab 2 ft or more below the snow surface.

    (2/9/2021) Example: Dry Loose avalanches start at a point and fan out as they run downhill. Don't get knocked off your feet or pushed into a terrain trap by one of these when there is so much snow. [Photo: Zack Wentz]

  • Persistent Slabs

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

    Observations on Thursday and Sunday documented that a weak facet/crust combination remains intact. This layer may produce avalanches with additional loading. Don’t expect obvious signs of unstable snow. If you dig in the snow, look for sugary facets above a stout mid-January crust about 2’ below the snow surface. You can use snow profiles and snowpack tests to track this layer, but don’t bet your life on a hole in the snow. The best way to avoid this sleeping beast is by staying off of large, steep slope on W-NW-N-NE-E aspects. Instead, seek out smaller, lower angled, and treed slopes.

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

Avalanche Discussion

We're expecting 6-8" of new snow Sunday night through Monday, with moderate winds. This will rapidly ramp up the avalanche danger.

You'll find about 8" of snow above the 2/7 crust with deeper drifts on lee northerly slopes. Light to moderate winds Friday night through early Sunday afternoon created isolated soft slabs before winds died down. Southerly slopes and ridgetops have been scoured. You might also find a very light rime/facet combo layer from 2/11 in your terrain that did not prove to be reactive on moderate angle slopes on Sunday.

The primary weak persistent layer we’ve been talking about for two weeks continues to sit in the snowpack. Observations from Hurricane Ridge on Thursday found small 1mm facets just above the mid-January crust on nearly all aspects. This layer failed easily in snowpack tests and showed the ability to propagate a failure across a slope. We have not received reports of an avalanche on this weak layer for some time and snowpack tests are beginning to show signs that the layer may be starting to heal. We are gaining confidence that you are unlikely to trigger these avalanches on southerly aspects or below treeline. You can help us track this persistent layer by submitting snowpack observations on our public site. 

While the Olympics are not the Cascades, this snowpack structure closely resembles other forecast zones across Washington. A very similar set-up resulted in several near-misses, avalanche involvements, and one fatality over the past week. (See the short video in the media gallery below for more information). If we can learn anything from these incidents, it’s that persistent slabs can be tricky and necessitate extra caution and patience. 

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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