Avalanche forecast

Olympics

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Wind slabs will be 3-4 days old by Tuesday and they are stubborn to trigger, but can still be large. Your danger will be greatest at upper elevations on steep or extreme terrain features and terrain rollovers. Look for clues such as cracking snow, whumphs, or tell-tale signs of wind-loading to identify potentially unstable slopes nearby.

Avalanche problems

  • Wind Slabs

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

    Friday night and Saturday's storm brought around 10" of snow, with 14" of snow now sitting on the 12/21 crust. Sustained moderate winds at ridgeline during the storm blew that snow around to create large slabs and cornices on N aspects. You can still trigger on specific terrain features such as 35 degree or steeper slopes with convex rollovers.  Your danger will be greatest near ridgelines and above treeline. Recent snow arrived with less wind, so your typical visual clues may be less useful. Dial back your terrain selection where you find a thin crust more than 12" below the surface, or a thicker crust more than 14" below the surface. These depth gauges will help you identify wind loading. Firm or punchy snow beneath the top few inches of snow could also be a good indicator. Whumphing or cracking of the snow also provides a quick indicator that you are heading into wind-affected and unstable snow. In areas where there is a firm slab, it could propagate widely and fracture above well above you on the slope. 

    Cornices are a relatively novel concern for the Olympics this season. Practice save travel and avoid traveling under corniced slopes, which are the same ones you should avoid due to their wind loading.

    (12/27/2020) Wind-slab example from an adjacent zone, releasing on a wind-loaded slope below fresh cornices.

Avalanche Discussion

Prepare for avalanche conditions to become significantly more dangerous Tuesday night and Wednesday as the next system impacts the Olympic Mountains.

Several inches of new snow fell on Sunday with light winds E/SE and S winds and gradually increasing temperatures causing the snow line to rise to around 4500 ft. The warming temperatures initiated some small rollerballs and point releases in the 4500 ft to 5000 ft range on Sunday. The sun came out on Monday to allow more widespread very shallow Wet Loose avalanches, many of which were initiated by falling snow (tree bombs).

Tuesday will feature increasing clouds and a chance for rain or snow to start late in the day. Weather inputs will be minimal during the day and should limit the Wet Loose activity unless precipitation arrives early. We expect a snow line around 4000-4500 ft, so rain on drier northerly aspects could trigger shallow Wet Loose activity. Mild temperatures through Tuesday should continue to help Wind Slabs heal at all elevations.

On Sunday, professionals found 14" of snow that was generally right-side-up and bonding, noting some reactivity above and below the stout 12/21 crust. This crust may provide a bed surface for any large avalanches. The crust limits our avalanche concerns to the snow that fell since 12/21. A minor crust may be found a few inches above the more obvious one.

Thin snow coverage still exists along ridgelines and at lower elevations. Give yourself extra time to deal with these travel challenges. 

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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