Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

The ongoing thaw will maintain tricky and dangerous avalanche conditions. Expect the likelihood and size of wet avalanches to increase throughout the day, while concerns for avalanches in wind-drifted snow still linger. It's uncertain how the snowpack will respond to this jarring transition from winter back to spring; build in a wide margin for error and consider avoiding avalanche terrain altogether.

Avalanche problems

  • Loose Wet

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

    Expect 9,500-11,000ft freezing levels for the next 24 hours. With such warm temperatures, snow surfaces won't have a chance to freeze and gain strength Wednesday night. Wet snow conditions will exist right out of the gate Thursday, and the strong April sun will beat down on the snowpack and accelerate the thaw. The most dangerous conditions will develop on E-S-W aspects in direct sun, but you could encounter wet snow on any aspect and elevation by afternoon. Avalanches will run naturally and will be easy to trigger on slopes 35 degrees and steeper. These avalanches may start small and shallow but could grow large and gouge deeper as it continues to heat up. Wet loose slides in motion could even trigger slabs resulting in surprising avalanches. Choose simple terrain away from large avalanche paths as the snowpack takes time to adjust to these dynamic conditions.

    (3/25/2022)

    Example: Natural wet avalanches on a steep sunny slope from earlier this winter. 

    Photo: Dallas Glass

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    All the recent storm snow is still settling and stabilizing. A large natural avalanche even occurred early Wednesday just outside of White Pass Ski Area. Slabs several thick could still be reactive to triggers Thursday, especially in unsupported rocky terrain at upper elevations. Look for clues like sharp drifts, fresh cornices, and textured surfaces to help anticipate and avoid potential wind slabs. As the sunshine and warm temperatures continue to affect the snow surface, it's hard to say how the storm snow will react. It could make slides easier to trigger. Additionally, large triggers like cornices and loose wet slides may cause the deep layers to fail. So, don’t let your guard down just because it feels like spring. Continue to avoid large steep wind-loaded features. 

    (4/2/2022) Use visual clues to anticipate and avoid wind loaded slopes.  Photo: Dallas Glass

Avalanche Discussion

It's rare to see such a cold winter storm immediately followed by such a dramatic warm-up. Wet loose activity was slow to develop Wednesday but the hazard should spike on Thursday. This may not be the average wet loose cycle you usually see during the first sunny days after a storm. These conditions are a very good recipe for avalanches due to:

  • The depth (2-3ft) and cold, low-density quality of new snow
  • Lack of an overnight freeze and 5000ft temperatures near 60F Thursday
  • Intensity and duration of the sun this time of year

We have a significant amount of uncertainty about how this day will play out. Don’t box yourself in by choosing routes that require you to travel through avalanche terrain to exit. As the warm temperatures increase our uncertainty grows and so does the potential for larger and more deadly avalanches. 

The recent snow sits above the Early April Crust. You can use this snowpack marker to easily measure the new snow, identify deeper/shallower locations, and focus your observations on the upper snowpack. We don’t anticipate any slides on older snow layers, but what’s left of the 3/8 weak layer and Early March Crust is still in the back of our minds. This warm-up and avalanche cycle could put it to the test.

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