Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

You may be able to trigger avalanches where the snow is wet and unsupportive and at upper elevations where you find shallow snow drifts of new snow. After a major rain storm earlier this week, cooling temperatures, light snow, and wind are slowly shifting avalanche conditions. Be ready to make your own assessments, as the avalanche conditions have changed significantly.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Watch for small drifts on leeward sides of ridges at upper elevations. You may be able to trigger small slab avalanches in freshly drifted snow. Steer around drifts and wind-loaded slopes steeper than 35 degrees.

    Temperatures cooled enough on Wednesday that new snow may have accumulated at upper elevations, while southwest winds were strong enough for transport. With more light snow and wind in the forecast, keep an eye out for small, subtle drifts. If you travel to wind-exposed ridges, be prepared to assess the potential for wind slab avalanches. We have little information about conditions at upper elevations over the course of the past week's big storm.

    (11/21/2023)

    An example of wind drifting snow near ridgelines. This is a clue that you may be able to trigger a winds slab avalanche.

    Photo: Matt Primomo

  • Wet Slabs

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

    A lingering chance for wet avalanches is maintaining moderate danger. While they're becoming less likely, the consequences are worth keeping in mind. Wet slabs could be large and could entrain mud as they flow downhill. Avalanches may encompass a variety of all things wet, including wet loose, glide slabs, and debris flows.  Glide slabs can release a large area of snow from overhead rock slabs or grassy slopes. If you find yourself sinking deep into wet, unconsolidated snow, don't go onto or linger underneath steep slopes and large features. 

    (12/6/2023)

    A small wet slab that likely ran on Dec 4-5th in the Salmon LaSac area in the neighboring East Central zone. This may have been triggered by a cornice fall from above. 

    Photo: Katie Warren

Avalanche Discussion

After a prolonged and wet and wild storm, the height of snow at Washington Pass still shows a net gain, at 35". Since November 30th, the weather station recorded nearly 5" of water equivalent, with the last 2" falling as rain. Freezing levels may have spiked at around 8,500ft Tuesday morning while heavy rain fell. Observations have been limited since rain began.

On Monday, observers reported whumphing collapses as low as 3,000ft and shooting cracks at higher elevations. They also spotted a recent natural slab avalanche beneath the cliff on Hinkhouse Peak (see photo below). Before November 30th, professionals found 2.5-5ft of snow between the eastern and western parts of the Highway 20 corridor. 

If you got out, please let us know what you found in the mountains by submitting an observation.

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