Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

You may be able to trigger small wind slabs as you ascend in elevation on Wednesday. Use visual clues such as fresh cornices to identify wind-loaded features to avoid. In some instances, you may need to feel for changes in the stiffness of the snow to find the problem spots.

Avalanche problems

  • Wind Slabs

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

    If you’re going to trigger an avalanche, it will probably be in a pocket of wind-drifted snow. Look for wind slab development on convex features, in confined chutes, or on the leeward side of ridgelines as you ascend in elevation. Although most of these should be small, they could be reactive - breaking on a crust or weak snow above it. Look for textured surfaces, pillow-like drifts, or fresh cornices to help determine wind-loaded features to avoid.

    In some areas, slabs may be hidden beneath an inch or two of fresh snow, making visual clues less helpful. Try to identify the features where wind slabs like to develop and avoid them. If you notice a density change in the snow while traveling, you may have stumbled upon a slab and should change course. 

    (12/31/2023)

    Visual clues of wind loading: rime in the trees, drifts behind objects, textured surfaces, and a sharp wind lip/small cornice line.

    Photo: Luke Schwettman

Avalanche Discussion

The storm was fashionably late on Tuesday but eventually delivered a few inches (and counting) to the West South zone. Winds were gusting into the 40s in the northern half of the zone at stations such as Sunrise and Crystal Mountain. The winds should slowly ease as snow showers continue into the evening before tapering on Wednesday. You may see some sun breaks in the afternoon.

Over the holiday weekend, new snow, sunshine, and periods of wind impacted the zone. The 12/30 crust was buried by new snow on Saturday. On Sunday and Monday, backcountry travelers reported rollerballs on sun-exposed or cloud-moistened slopes. Additionally, wind-affected snow was found at upper elevations and on the volcanoes. Variable and sometimes weak surfaces were observed prior to Tuesday’s snowfall. We suspect most of these weak grains were wiped out by the wind or are too shallowly buried to cause much of an issue at this point in time.

Our main layer of interest in the upper snowpack continues to be the 12/25 interface. This crust/ice lens has produced propagating test results as recently as Monday and can be found in the top foot of the snowpack. This is the layer we’ll be watching as our week hopefully gets snowier.

Look out for those open creeks, small bushes, rocks, and holes. They’re still out there, especially at lower elevations where they can impede travel. 

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