Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Another round of rain and warm temperatures may result in wet avalanche problems on Thursday. If you’re not standing on a firm crust, then you should start to think about the potential for these avalanches to occur. If you’re on the highest peaks or upper elevations of a volcano, you could find some unstable pockets of wind-drifted snow to steer around by day's end.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    We haven’t received a whole lot of snow since the last time it rained, which should minimize the size of wet avalanches on Thursday. However, if you find that the snow surface is sticky and wet and you are sinking in past your ankle, you should have wet avalanches on your mind. Wet Loose avalanches will be more likely on steep slopes over 35 degrees where there is enough surface snow available to entrain. Rollerballs and pinwheels are often the first indicators of Wet Loose avalanches, and you can look at their size on Thursday to determine if there is enough snow available for entrainment. If you suspect wet avalanches, head for lower angled slopes, keeping aware of terrain above you.

    The rain can also cause other types of wet avalanches such as cornice collapses or glides. Although the zone has undergone multiple rounds of rain recently, some of these difficult to predict avalanches may not have reached their tipping point. Don’t get caught below these ticking time bombs if Thursday’s rain is the last push needed for them to fail.

    (1/16/2022)

    Wet loose avalanches on an east aspect near 6800ft on Hogback Mountain. Look for similar avalanches due to the incoming rain on Thursday.

    Photo: Public Observation

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    The highest of elevations may be able to escape the bulk of the rain, particularly as the day wears on and temperatures start to cool. Locations such as the volcanoes could pick up several inches of snow that are drifted around by moderate to strong winds to create Wind Slabs. If you venture up to these heights, look for textured snow surfaces or actively blowing snow to help you determine where there are pockets of wind drifted snow to avoid. These slabs will be more likely on leeward ridgelines or near rocky features such as the base of cliffs or the sides of gullies and chutes. 

    (1/15/2022)

    A skier-triggered avalanche on an east aspect near 7500ft on Mt St Helens. The avalanche broke in wind drifted snow 12-18in deep long after the storm had subsided. If you're high on a volcano, you could find avalanches in similar terrain on Thursday.

    HS-AS-R2-D2

    Photo: Jeff Zimmerman

Avalanche Discussion

Our warm and wet weather will continue on Thursday as rain again reaches into the above treeline line band. We expect the height of instability to be overnight on Wednesday, lingering into Thursday morning when the heaviest rain is expected. Only the highest elevations will avoid the rain overnight. As snow levels slowly drop throughout the day, you could find some fresh flakes falling toward the upper reaches of the near treeline band. 

Generally speaking, the existing snowpack around the zone should be well suited to handle the incoming rain. Multiple rounds of rain and warm temperatures the past week have created drain channels in the snowpack at many elevations and resulted in a series of crusts. In most locations, these crusts should be able to withstand the amount of precipitation forecasted, but if you find that they are breaking down and liquid water is making it to deeper layers of the snowpack, larger avalanches could occur.

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