Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Dynamic springtime weather has left us with a variety of avalanche problems to manage.  Avoid unsupported slopes, convex features, or wind-loaded terrain where triggering a slab is more likely. If you're sinking into moist snow deeper than your ankle, wet avalanches could follow.

Avalanche problems

  • Storm Slabs

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

    As you ascend in elevation, you'll encounter drier snow and the potential for slab avalanches. They'll be more likely on unsupported slopes, convex rollovers, or in wind-loaded terrain such as confined chutes or the base of cliffs. Slabs could be possible at elevations with moist snow but may be more stubborn. Use quick hand pits to look for potential layers of concern. Uptrack tests and small test slopes can help you gauge how the snow reacts to your weight as a traveler. Visual clues like large drifts, textured surfaces, or "fat pillows" can help you identify loaded features.  Avoid steep features over 35 degrees if you see any signs of instability.

    (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

    Daytime warming, sun breaks, or rain showers could destabilize the snow surface and create the conditions for wet avalanches. Heavy wet snow already exists in many areas and is waiting for something to help push it downhill. Once these slides get moving, they can grow large and powerful as they descend and gather snow. In some areas, they could even trigger slabs. If the snow surface is wet and weak and you see new rollerballs, pinwheels, or snow shedding from trees and rocks, head for lower-angled terrain.

    In isolated locations, larger, more unpredictable shed-style avalanches could occur. Keep an eye on the terrain above you, and don't linger where you see precariously hanging blocks of snow.

    (3/27/2024)

    This loose avalanche triggered a small storm slab on the slope below. 

    Photo: Dallas Glass

Avalanche Discussion

Our snowy but warm storm cycle is starting to peter out. Snow showers should focus on the volcanoes on Friday, but you'll likely see an inch or two in other areas. Any new snow will further build depth over last week's warm-up crust. We expect all avalanche activity to occur in the 1-2 feet of recent storm snow above this easily identifiable interface. 

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 near Crystal Mountain triggered wind slabs in confined rocky terrain. On Thursday, White Pass Pro Patrol reported that the snow started to "slab up" with daytime warming, making it more reactive. 

Be ready for rapid changes in weather and snow stability as we head into the heart of spring. Intense storms can give way to sun and microwave-like warming in a matter of minutes - and then turn back to snow showers by the afternoon. Dry snow avalanche problems can quickly turn into wet snow avalanche problems, or you might see both simultaneously on slopes with different aspects.

Low elevations have less snow than average after repeated rain and warming events throughout the winter. Expect shallow coverage, open creeks, and punchy wet snow. Sporadic snow showers with fluctuating freezing levels will allow coverage to wax and wane along with wet avalanche activity.

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. 

 

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