Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Another round of springtime weather will result in snow, wind, and fluctuating freezing levels in the West South on Thursday. Avalanche problems will transition from wet to dry as you ascend in elevation. You're more likely to trigger a slide on slopes over 35 degrees, regardless of the snow's moisture content.

Avalanche problems

  • Storm Slabs

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

    As you ascend in elevation, the likelihood of dry snow problems increases. Slabs are still possible at elevations with moist snow, but they may be more stubborn. Use quick hand pits to check for layers of concern or a poor bond to the underlying crust. You may find heavy snow over softer snow due to fluctuating freezing levels, resulting in a storm slab problem. Look for textured surfaces or fresh drifts to help identify wind-loaded slopes. Uptrack tests and small test slopes can help indicate how these problems react to your weight as a traveler. You're more likely to trigger a slide on slopes over 35 degrees, so when in doubt, default to lower-angled terrain.

    (3/27/2024)

    A storm slab avalanche that failed on a steep convex slope.

    Photo: Dallas Glass

  • Loose Wet

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

    Thursday should be a notch warmer than Wednesday, meaning rain will reach higher, and existing snow will be heavier.  Look to the snow surface to help determine when and where wet avalanches could occur. If you are sinking into moist snow deeper than your ankle, see new rollerballs, or notice snow shedding from trees and rocks, you should anticipate wet avalanches. These slides often start small but can grow large as they descend and fan out. They'll likely be heavy and can be deceivingly powerful. Don't get tripped up by one near a terrain trap where the consequences could be amplified. 

    (3/18/2024)

    A skier-triggered wet loose avalanche that entrained snow as it gouged into older layers. 

    Photo: Crystal Mountain Pro Patrol

Avalanche Discussion

Thursday should be a notch less stormy than Wednesday. We're still anticipating moderate precipitation and winds, but it should be a bit warmer. Expect a transition from wet to dry avalanche problems as you ascend with a mix of the two near the fluctuating rain/snow line.

On Wednesday, a gaggle of PNW avalanche forecasters were at Chinook Pass and reported natural and human-triggered slab avalanches as large as D2. Most of these occurred on convex features or unsupported slopes. They reported heavy moist snow, rollerballs, and small loose avalanches at lower elevations. Skiers at Crystal Mountain reported elevation-dependent moisture content of the storm snow and shallow slabs failing in rocky terrain.

This week's snow has increased the depth over a crust formed from last week's warm weather to roughly 1-2 feet. We expect all avalanche activity to occur above this easily identifiable interface on Thursday.

Deeper in the snowpack, you can still find facets on and near the Early February Crust, but these layers have significantly gained strength. Additionally, they are becoming bridged by the crust mentioned above. It would likely take a very large trigger in rocky, shaded terrain to produce a slide. 

The lower elevation snowpack took a massive hit during the recent warm weather. Expect shallow coverage, open creeks, and punchy wet snow. As temperatures fluctuate throughout the week, coverage will wax and wane along with wet avalanche activity.

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