Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

A pair of natural avalanches failing on weak older snow Wednesday punctuates the dangerous conditions some parts of the zone continue to experience. Keep your terrain choices dialed back and stay off of open slopes greater than 30 degrees.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    On 02/03 Crystal Mt Ski Patrol reported a pair of natural avalanches that failed overnight on facets just above the 1/13 crust. These latest slides only add to the near steady stream of natural and human-triggered avalanches that began last Wednesday (1/27). Recent avalanches provide clear evidence that unstable snow exists in the upper snowpack. Some slides triggered remotely, stepped down into older layers, and triggered other avalanches. This is not a problem to try to outsmart. You can use snow profiles and snowpack tests to track these layers, but not as decision-making tools. Stay away from open slopes greater than 30 degrees. 

    If you dig in the snow, look for sugary facets just above a stout crust (1/13). In many locations, they sit 24-36” below the surface. In some instances, buried surface hoar and/or a thin crust accompany these persistent grains. This general snowpack structure has been reported on a variety of aspects and elevations all across the forecast zone.

    (2/3/2021) This natural avalanche likely occurred overnight on 02/02 in non-skier compacted terrain within Crystal Mt Ski Area. It failed on 1-2mm facets just above the 1/13 crust. 6300' NNE aspect. 85-95cm deep. Photo: Cyrstal Mt Ski Patrol

  • Wind Slabs

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

    Winds should increase on Thursday afternoon and transport the recent snow onto the lee sides of ridges. Blowing snow should serve as your first and simplest clue for newly forming wind slabs. You may also notice slightly deeper areas of soft snow or subtle drifts behind objects that indicate which slopes could harbor wind loading. Steer around these fresh drifts and seek out lower angled or less wind affected terrain. Older, deeper wind slabs from the past several days could linger in some areas. You'll need to do a bit more detective work to find them. Look for scoured slopes and larger wind features to locate and avoid these potential older slabs.

    While we expect wind slabs across the entire zone, on some slopes these wind deposits may overlay a persistent weak layer. In these areas, wind slabs may trigger easily or break wider than you might expect. Put plenty of distance between you and any wind loaded slopes.

    (2/2/2021) Blowing snow like this can help you identify which slopes to avoid. East Peak, Crystal Backcountry. Photo: Shane Robinson

Avalanche Discussion

The West-South zone should see increasing winds and snowfall by the afternoon. The new snow should not significantly increase the avalanche hazard. While you are most likely to encounter wind slabs throughout the zone, persistent slabs continue to pose particularly dangerous conditions in some areas. The overwhelming majority of avalanche observations come from the Crystal backcountry. This does not mean that the persistent slabs are not a problem in other locations. Avalanches near White Pass and Mt St Helens over the weekend indicate the presence of persistent slabs in these regions. So far, no avalanches have been reported from the Paradise and Tatoosh areas, but snow profiles show a very similar structure. It may take some time for this layer to finally heal. Continue to exercise patience. You can continue to help us track this layer by submitting observations on our public platform. 

Below 5000-5500’, a rain event on Monday (2/1) formed a thin crust now buried by a few inches of snow. At these lower elevations watch for breakable crusts and difficult travel conditions.

Regions covered