Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

You can trigger avalanches in, or just under, the new snow.  In the eastern mountains and foothills, you may be able to trigger surprising avalanches that could break widely across terrain features. Incoming snow will bring gradual warming with a chance for wetter snow or sleet over the weekend.

Avalanche problems

  • Loose Dry

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

    On Friday, most triggered avalanches will involve the new snow and will likely be loose and dry. If you do encounter shooting cracks or more cohesive new snow, anticipate that it could break as a slab avalanche. Avalanches could be large if they dig down into snow that fell since the 18th. Use small test slopes and quick tests to anticipate how the snow might break before committing to bigger terrain.

    Expect snow totals nearing 10" near Washington Pass by the end of Friday. While temperatures will warm, we expect that a high in the teens will keep most snow surfaces very light and dry. New snow will be covering slabs that were drifted by southwest wind on Wednesday. You may still be able to trigger slab avalanches on leeward slopes above treeline. There's quite a bit of uncertainty about the weather for the next two days, so be prepared to make your own observations. 

    (2/27/2022) An example from last season of a natural loose dry avalanche in the Cutthroat creek drainage. Photo: Josh Hirshberg

  • Persistent Slabs

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

    Near and east of Mazama consider the potential for triggering dangerous and surprising avalanches. With the ongoing loading of new snow, keep an eye out for signs of instability. If you see cracks shooting through the snow, experience loud collapses, or find strong over weak layers that produce sudden or propagating test results, stick to lower-angled slopes. You'll find a weak layer of facets in the lower half to third of the snowpack and often under one or two crusts. 

    Triggering an avalanche on older weak layers near Washington Pass and the Cascade crest isn't out of the question. Some avalanches on the 20th were suspected to have involved the December 8th surface hoar. A few observations during past loading events indicate that persistent slab avalanches on weak layers in the lower snowpack could be possible near valley bottoms and in isolated areas above 7,000ft, where the mid-November facets are still weak. If you hit the wrong spot, you could trigger a dangerous avalanche.  

    (12/18/2022)

    Very small persistent slab avalanches released on unsupported features when a skier approached from above.  Silverstar - Below Treeline

    Photo: Katie Warren

Avalanche Discussion

Extremely frigid temperatures have limited backcountry travel and information. The low temperature early on Thursday morning was -27 degrees Fahrenheit! Friday's forecasted high of 15F will feel relatively balmy. The incoming storm will bring warmer temperatures as we enter the weekend. It remains to be seen just how warm it will get and if we'll receive any rain. We anticipate that the weather models may face challenges in forecasting this unique storm and temperature scenario.

The mountains close to the Cascade crest picked up close to 20" of snow through Tuesday. On Tuesday, observers near Cutthroat Lake reported two larger natural slab avalanches likely due to new snow and wind loading. At least one of these may have run on older weak layers around 7,200ft, ENE in Swamp Creek (see photo below).  Observers continue to report lots of collapsing and cracks shooting through the snow in the eastern foothills. On the 18th, an observer triggered a small avalanche on an unsupported northerly feature below treeline in the Silverstar drainage. The slide ran on the mid-November facets. 

The December 18th interface holds weak grains of small facets, surface hoar, and crusts on southerly aspects. You may be able to find buried surface hoar from December 8th about 2 feet below the snow surface.

Regions covered