Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

A night of warm temperatures followed by high elevation rain Thursday will cause concern for wet avalanches. Avoid large open slopes greater than 35 degrees where you find wet and unconsolidated snow.  Keep glide cracks and cornice fall in mind, and continue to steer around slopes where these hard-to-predict hazards exist.

Avalanche problems

  • Loose Wet

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

    Light rain to 5000ft will create the potential for wet loose avalanches. Of most concern are northerly slopes near treeline steeper than 35 degrees, or anywhere rain falls on dry, cold snow. Precipitation looks to begin early Thursday, and the greatest wet loose hazard will exist by the end of the day. Wet loose slides could even run naturally. It's not out of the question to see these avalanches grow large in isolated areas. Watch for changing conditions throughout the day and keep an eye out for fresh rollerballs and pinwheels. Minimize your exposure to large steep open slopes during periods of rain, and stick to lower angled terrain anywhere you encounter a wet unconsolidated upper snowpack. 

    (3/17/2021) Recent wet loose activity in steep, rocky terrain on the east aspect of Mt. Herman in the West North Zone.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Above the rain-line, a few inches of new snow and strong southerly winds could form fresh drifts in leeward terrain. Areas of wind drifted snow will begin to form Thursday, and will likely thicken and become more reactive as the storm continues Friday. Carefully assess how new and wind drifted snow bonds to variable old snow surfaces. If you venture out during the storm, ease into alpine terrain slowly and watch for cracking, collapsing, and recent avalanches. Be cautious near ridge crests and convex rollovers 35 degrees and steeper where you find evidence of wind drifted snow. 

    (3/16/2021) Watch for wind-textured and rippled snow surfaces like these as indicators of a potential wind slab problem.

Avalanche Discussion

NWAC field teams traveled to the  Whitehorse Mountain area on Wednesday and reported plenty of cold, dry snow and good riding conditions in northerly terrain above 4000ft. Below, and on E-S-W aspects, snow surfaces were variable and heavily affected by sun and warm temperatures. In these areas, loose wet activity was widespread but small and ran primarily during the first full day of sun on Tuesday. Cornice fall avalanches occurred during the recent warm, sunny weather. Continue to stand back from cornices along ridgelines, and give them a wide berth from below. Several large glide cracks and a few glide avalanches were observed as well. These avalanches are difficult to predict, but if you notice crevasse-like cracks in the snowpack, avoid these slopes and areas below. Keep cornices and glide cracks on your radar as the snowpack continues its spring transition with more warm, wet, weather over the next 24 hours. The incoming weather may be enough to raise the avalanche danger to Moderate by afternoon, but the greatest impact from the beginning of the storm Thursday may just be deteriorating snow/riding quality.

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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