Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Tuesday could be a dangerous and tricky day where you need to manage very different avalanche concerns. The dynamic weather won’t help. So, choose terrain that’s simple and gives you lots of options to identify and easily avoid avalanche terrain when needed.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    Strong and gusty winds continue to define this storm and its primary avalanche concerns. This sustained wind event should last through at least Tuesday morning (if not longer). Expect wind slabs to continue to grow and even form in new areas. Because of the gusty nature of these winds, you may find wind slabs in some very strange places like far below ridgeline, along the sides of features, down in the trees, and even in your go-to powder stash. Unless you’re standing on a scoured slope, you should anticipate wind-affected snow. At this point, there could be several possible weak layers to fail and could result in shallow or very deep avalanches. Needless to say, this isn’t our normal wind slab issue and not a time to try and thread the needle. Look for blowing snow, sharp drifts, and firm slabs to help identify loaded areas. Then steer away from all steep wind-affected slopes. 

    Even though we aren’t expecting a natural avalanche cycle, you may still see a few slides. These will be most likely at upper elevations and in complex rocky terrain. This isn’t a time to linger underneath any large open slopes especially when they are capped by a looming cornice.

    (4/2/2022) Signs of possible wind slabs can help you anticipate possible wind-loaded locations. Photo: Dallas Glass

  • Loose Wet

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

    There’s lots of fresh snow on the ground and it won’t take much sunshine to start a loose wet avalanche cycle. Many of these slides could easily grow large enough to bury and kill you. So, you’ll want to pay close attention to the sky. If you start to experience significant sun breaks, the time has come to get out from under steep sunny slopes. While rollerballs and other avalanches will be great clues, don’t wait that long. If the sun comes out, immediately start thinking about this problem. If, however, the sky stays mostly cloudy, this likely won’t be an issue at all.

    (1/16/2022)

    Example: Natural wet loose avalanches on an east aspect near 6800ft on Hogback Mountain from earlier this winter. 

    Photo: Public Observation

Avalanche Discussion

This storm has really piled up quite a bit of snow in a short time across the West South zone. As of 5pm, Tuesday storm totals range from 18-24” and counting. Our weather stations have recorded strong winds throughout nearly the entire storm with gusts frequently reaching into the 60-80mph range. (White Pass and Muir topped 100 mph). This new storm snow accumulated over the Early April Crust. On some shaded slopes, a few inches of snow capped this layer prior to the storm. You can use this snowpack marker as a way to determine the storm snow depth and find wind-loaded/stripped areas. It can also help you focus observations on the upper snowpack. We generally believe, avalanches will be limited to the new storm snow above this crust. However, there still is some uncertainty about the Early March Crust and what’s left of the weak snow above it. At this point, it would likely take a very large trigger like a cornice or other avalanches to cause avalanches on this old snow layer, but given the ongoing storm, some uncertainty exists. That’s just one more good reason not to hang out in locations where avalanches can run and stop on Tuesday.

Regions covered