Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

A late-season storm is increasing the danger of slab avalanches in wind drifted snow. Assess new wind slab layers before moving into avalanche terrain. Fall back to lower angle slopes if you find conditions different from what you expect or if poor visibility makes it difficult to evaluate the terrain around you. Brief periods of clearing sky could initiate wet avalanches on sun-exposed slopes.

 

Avalanche problems

  • Wind Slabs

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

    Up to 6” of new snow and moderate - occasionally strong - alpine winds will build fresh wind slabs overnight into Tuesday. You are most likely to find one of these in steep mid and upper elevation terrain where the wind created thicker and easier to trigger slabs. Look for signs of recent wind loading like differences in snow texture and depth as you gain elevation and change aspects. Cornices and wind eroded or scoured snow surfaces might point to areas that are more likely to hold new wind slabs. Basic observations like hand shears and stomping on test slopes can help you gauge the bond of wind slab layers. When in doubt just steer around steep wind-loaded features and slopes to avoid triggering an avalanche.

    Small wind slab avalanche from earlier this winter. Intentionally triggered beneath a ridgeline on Lichtenberg Mtn (NE at 5,600ft - Stevens Pass).

    Photo: Ryan Minton

Avalanche Discussion

With the bulk of the snowfall forecast for the overnight hours, avalanche danger should be the greatest in the morning with a gradual increase in stability throughout the day. The caveat is danger will remain elevated if snowfall persists longer than forecast or in areas seeing continued wind-loading. Wet loose avalanches are possible if new snow warms, becomes wet, and weakens on sun-exposed slopes or at low elevations. Minimize travel on and below slopes where you see wet loose avalanches or other signs of instability during sun breaks or with rising temperatures. 

A period of drier weather and generally clear skies ended Sunday evening as a well-developed frontal system moved into the Cascades. West Central received light precipitation Monday with snow levels hovering just below treeline. New snow will fall on a variety of surfaces from a slick, stout crust on solar aspects to cold and dry snow on the most shaded aspects. Some shaded slopes also held onto surface hoar, facets, and even graupel layers that could enhance the reactivity and propagation of wind slabs. Though not widespread, they are another reason to approach avalanche terrain holding 6" or more of new snow with additional caution on Tuesday.

 

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