Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

You’ll need to manage developing wet and lingering wind avalanche concerns on Friday. Fortunately, the snow surface conditions will help clue you into slopes you may want to avoid for both issues. If you find wet/sticky snow or wind-textured surfaces avoid similar nearby steep slopes.

Avalanche problems

  • Loose Wet

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

    There’s plenty of fresh snow on the ground that could produce avalanches if the sun comes out on Friday. Fortunately, brief periods of sunshine the past few days likely helped some of this snow settle and form a crust. So, while we are expecting natural loose avalanches, this shouldn’t be a widespread cycle. Keep an eye on the snow surface. When you see the crust breaking down, find wet, sticky snow, or notice new rollerballs, anticipate loose wet slides and blocks of snow shedding from rocky terrain. Pay attention to the slopes above you and limit the amount of time you spend on and under steep terrain during these warm and sunny periods. 

    At lower elevations, warm temperatures this week and substantially less snowfall should limit the loose wet avalanche activity. However, the snowpack below treeline may be wet and punchy even without the sun. You may be able to push a small loose avalanche in very steep terrain. Even though these slides should be tiny, they can still carry you places you don't want to go like into a creek or over rocks. 

    (3/24/2022)

    Example: Warm sunny weather caused these rollerballs, loose wet slides, and chunks of cornice to fall downhill earlier this winter on Mt St Helens. 

    Photo: Andrew Kiefer

  • Wind Slabs

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

    The wind drifted snow throughout this week, including Wednesday night and Thursday. Even though these wind slabs are becoming harder to find and tough to trigger, keep them on your radar for at least one more day. If you managed to stumble into one of these lingering slabs it could fail 1-2 ft deep and easily be large enough to bury you. Look for textured surfaces and sharp drifts to highlight potentially wind-loaded slopes you may want to avoid. Because the winds frequently switched directions, you could find wind-affected snow on a variety of aspects and even on slopes that normal are stripped by the wind. 

    (4/2/2022) Example: Signs of wind-affected snow can help us anticipate possible wind slab locations. Photo: Dallas Glass

Avalanche Discussion

While snow showers could bring another few inches of snow to the West South zone Thursday evening and Friday afternoon, it shouldn’t be enough to generate much of a hazard. Instead, it will only add to the solid snow totals from this week’s storms. Since Monday (4/18), most locations around the zone have received 12-18” of snow. The bottom of these storms is marked by a melt-freeze crust on most slopes. While you may find a variety of thinner, breakable crusts that indicate sunny moments between showers this week, the lower 4/18 layer will help you measure the recent snowfall and highlight wind-loaded/stripped locations. As temperatures warm, avalanches could involve any of the snow since this past Monday (4/18).

A more prominent crust (4/8) is found 3-4 ft below the surface in most areas and marks the bottom of the upper snowpack. While we aren’t expecting avalanches this deep on Friday, we are watching these snow layers as we head into a warmer weather pattern this weekend.

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