Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Wed
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Out of date — this forecast expired 5 years ago.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

Relatively quiet weather should allow the snowpack time to gain strength. Even so, you may still encounter potential avalanches in wind-affected snow or in larger slide paths. Choose terrain where you feel confident and comfortable in your ability to reduce your risk by where and how you travel.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Shallow wind slabs formed in many areas of the West South on Sunday. A changing wind direction Monday may have redistributed some of this snow onto other aspects. As a result, you could encounter shallow drifts on a variety of exposed features at mid and upper elevations. Use caution on steep slopes below cornices, near rocks, or in confined chutes where encountering wind slabs may be more likely. The look and feel of the snow surface may act as your best clues. When you see a textured snow surface or feel the snow become deeper/firmer beneath you, expect wind slabs on similar slopes. Don’t let these thin slabs surprise you, knock you off your feet, and carry you into a terrain trap such as a rock or cliff.

    (3/7/2021) We intentionally triggered this small wind slab on a test slope near treeline. Small features like this can help highlight conditions on larger slopes. NW, 6100'. SS-ASc-D1-R2-S

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    The lack of recent avalanches, a strengthening upper snowpack, and favorable weather continue to slowly build our confidence. However, a nearly month-long avalanche cycle complete with crowns 6-8’ deep, fractures hundreds of feet wide, and debris littered with broken trees hangs fresh in our memory. (see media gallery) Keep this high consequence avalanche problem a central part of your discussions before entering larger and more complex avalanche terrain. Limit your time in and under big avalanche paths including near valley bottoms where they mat run or stop. Other small avalanches or failing cornices could still wake this sleeping beast, resulting in a catastrophic avalanche that would almost certainly be unsurvivable.

    (2/27/2021) This very large and destructive deep persistent slab was reported by multiple parties on Saturday 2/27. While we don't know exactly when it occurred, it is very recent. E, 6300' 6-8' deep. Union Creek HS-N-D3-R4-O Photo: Joe Hoch

Avalanche Discussion

Some uncertainty around the sky cover, and ultimately the impact of the sun, exists in Tuesday’s weather forecast. We expect cloudy skies for much of the forecast area. If you experience more sunshine, anticipate natural loose wet avalanches. Watch for new rollerballs or sticky snow surfaces as your first clues. When you notice these signs, steer around similar slopes.  In some locations like Paradise and Mt St Helens, enough soft snow may sit at the surface to allow a few of these slides to grow larger. 

The West-South zone received 3-8” over the weekend. Passing showers may add an additional inch or two by Tuesday afternoon. This new snow should not significantly impact the avalanche hazard. Recent windy weather created drifts and scoured slopes on exposed terrain. All this recent snow sits over a new crust (3/5) and a generally strong upper snowpack. You may still see many of the interfaces and crusts discussed over the past month, however, the primary layer of concern remains the mid-January facet-crusts combination. This layer sits 6-10+ ft below this snow surface. Snow profiles and avalanche events documented this layer in all areas of the zone. The last confirmed avalanche occurred the weekend of 2/27-28. Even as we gain confidence and the avalanche danger slowly drops, don’t let this layer drift from your mind. 

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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