Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Look out for reactive pockets of wind-blown snow as you ascend in elevation to where the snow is colder and drier on Sunday. Freshly built cornices or textured snow surfaces can help you to identify wind-loaded features to steer around. On the volcanoes, expect to find thicker slabs than near the crest.

Avalanche problems

  • Wind Slabs

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

    Continued snowfall combined with moderate winds may further develop shallow Wind Slabs on the lee side of ridgelines or other exposed features on Sunday. As you ascend in elevation, keep an eye out for small drifts, fresh cornices, or textured snow surfaces to help clue you in to the existence of nearby Wind Slabs. You’re most likely to trigger one of these slabs near the base of cliffs or on rocky slopes such as confined gullies. Using test slopes or uptrack tests can help you identify if the recent snow has slab potential and how it may react to your weight.

    (3/20/2021) This Wind Slab was intentionally triggered by a cornice drop on Saturday in the Crystal Backcountry. One of the deeper slides found by NWAC forecasters, it released 8-10" deep. [NW 6300'; SS-ASc-D1-R1-S]

Avalanche Discussion

Sunday will be the third day in a row of snow and wind in the West South. Although we may get a relative break in the weather before more significant precipitation arrives on Sunday night, the inputs should be enough to maintain hazardous conditions throughout the zone. On Saturday, NWAC forecasters in the Crystal Mountain area were able to trigger over 12 small Wind Slab avalanches, mostly on North or East aspects,  and drifts as large as 2 feet were found. These triggered slabs were pretty small, but illustrate that touchy conditions existed. While this was going on, across the valley Paradise was receiving 10” of new snow throughout the day on Saturday, while Chinook Pass received closer to 8” and White Pass was closer to Crystal with 3”. With a bit more snow coming and the winds continuing to blow, expect to be dealing with similar conditions on Sunday throughout the zone, where you could find sensitive slabs and fresh cornices that are primed to fall. 

Beneath the recent storm snow, you will find a variety of surfaces, including breakable crust, firm melt-freeze crust, wind-stiffened snow, cold dry snow, and possibly faceted snow. These surfaces vary based largely on aspect or elevation, so take the time to investigate the bonding and potential for avalanches to run far and fast on a crust in the location you are in. If you are at lower elevations, you may find that the snow is wetter and heavier, having the make-up for Wet Loose avalanches. Although you could see some rollerballs or push snow on some features, we don’t believe there is enough recent snow to really drive a hazard at lower elevations at this time.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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