Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Increasing winds could transport snow into fresh slabs at mid and upper elevations. Watch for blowing snow to identify potentially wind-loaded features you want to avoid. In the eastern mountains and valley foothills, you may trigger a large avalanche especially if you see cracking or feel collapsing.

Avalanche problems

  • Wind Slabs

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

    You could encounter a fresh batch of wind slabs Saturday that may trigger easily. This will add to the patchwork of wind-loaded features that formed this week. While blowing snow will help you locate the new slabs, you’ll also want to identify and avoid smooth pillow-like drifts that formed over the past several days. Since the winds shifted from northerly to westerly, you may find wind-affected slopes on a variety of aspects and could encounter irregular loading patterns. Steer around these steep pockets of wind-drifted snow.

    (12/3/2022)

    Actively blowing snow, freshly building sharp cornices, and textured surfaces. All easy-to-identify signs of wind-loading. Look for slabs to develop on the slopes on the left side of the picture.

    Photo: Dallas Glass

  • Persistent Slabs

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

    The problem primarily seems to exist for the mountains near and east of Mazama where you could trigger one of these large avalanches. Several observations from the foothills of the Methow Valley clearly demonstrate unstable snow at lower elevations. Stick to lower angled slopes if you see shooting cracks, feel sudden collapses, or hear whumpfs from the snowpack. If you dig in the snow in these areas, you may find a layer of weak sugary facets in the lower portion of the snowpack. Sometimes these grain exists under one or two crust. 

    We don’t anticipate persistent slabs are a common problem near Washington Pass and the Cascade crest. However, during the last storm (12/9-10) a few avalanches indicated the mid-November facets may still linger near valley bottoms and in isolated areas above 7000 ft.

    (12/14/2022)

    Large avalanche crown running across the top of an east-facing slope in Finley Canyon, southeast of Twisp.

    Photo: Public Obs

Avalanche Discussion

An approaching storm will finally draw our week of nice weather to a close Saturday. The major impacts should come from increasing clouds and strengthening alpine winds. Precipitation should hold off until after sunset. This will do little to significantly impact the avalanche danger. 

On Wednesday, a large avalanche was reported from Finley Canyon. This slide occurred on an E aspect, propagated over 500ft wide, and likely involved the mid-November facets. This avalanche follows numerous other observations of cracking and collapsing in similar terrain. 

In the Washington Pass area, observations from this week show two potential weak layers worth keeping on your mind. Buried surface hoar (12/8) may be found about a foot below the surface in some locations. The more widespread mid-November facets continue to produce significant test results in a few areas. Even though these potentially persistent weak layers exist, a lack of recent avalanches in the area suggests they are not a current problem.

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