Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Rain and high-elevation snow will continue in the West South zone through Monday. The heaviest precipitation is focused on the volcanoes, where you will likely find dangerous avalanche conditions. Avalanches will be easier to trigger on slopes over 35 degrees, whether they are wet or dry.

Avalanche problems

  • Storm Slabs

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

    Snow is expected to continue at upper elevations, particularly on the volcanoes. This should result in multiple storm interfaces and potentially an upside-down snowpack. Use quick hand pits and small test slopes to check for points of failure and the bond to the underlying 1/20 interface. Triggering an avalanche will be more likely on slopes over 35 degrees or in wind-loaded terrain. 

    (1/19/2024)

    A natural storm slab avalanche that likely failed on the 1/16 interface. NE 6400ft. 

    Photo: White Pass Ski Patrol

  • Loose Wet

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

    Expect rain at lower elevations, possibly kicking off another round of wet avalanches. As temperatures creep up in the afternoon, middle elevations could be the target zone where rain falls on dry snow, resulting in more widespread activity. These avalanches often start at a point and fan out as they descend, growing larger and possibly triggering slabs. If you notice new rollerballs and pinwheels, fan-shaped avalanche debris, or rain falling on dry snow, it's time to avoid slopes over 35 degrees.

    (1/21/2024)

    Rollerballs are a good indication that wet avalanche activity is possible. 

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    NWAC forecasters and avalanche professionals continue to get concerning test results on the Solstice Crust. A public observation from Saturday evening pointed out a previously unknown, very large avalanche near Crystal Mountain. Seems like we get a report of a new one every few days. Although their occurrence dates are unknown, the structure is well documented. These slides can fail without warning and may happen at any time. Limit your exposure to large open slopes where one of these unsurvivable avalanches could occur.

    (1/20/2024)

    Crowns along the ridge from Scout Pass to Norse Peak. A newly discovered widely propagating avalanche with a 3+ foot crown.

Avalanche Discussion

We're trending back to our pre-holiday pattern after a few weeks of cold and snowy weather. Expect high-elevation snow and low-elevation rain, resulting in elevation-dependent avalanche problems. The volcanoes are driving the hazard rating on Monday with areas near the crest expected to be a notch lower due to size and likelihood. The problem set should hold throughout the zone.

Saturday resulted in a mixed bag of precipitation and conditions. It was a bit snowier than expected. Several parties reported heavy and wet new snow, creating a favorable bond to the underlying surface. In many areas, that surface is a rain or freezing rain crust (1/20 interface). This could be an excellent sliding surface for potential avalanches going forward.

Other interfaces in the upper snowpack, such as the 1/16 and 1/8, could still contain weak grains capable of producing surprising avalanches in isolated locations.

Regions covered