Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Continued snowfall and wind will maintain dangerous conditions in the alpine. You can trigger small to large avalanches in wind drifted snow along ridgelines and in leeward terrain. Use visual clues to identify and avoid wind-loaded slopes greater than 35 degrees and use caution around and below cornices. 

Avalanche problems

  • Wind Slabs

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

    Weather forecasts call for steady precipitation in the northern half of the West Central Zone over the next 24 hours with an additional 6-12in of new snow. Less snow means less avalanche danger. If the weather forecast does not verify, or in the southern half of the zone where just a few inches of new snow are expected, the avalanche danger may be one step lower. 

    The most dangerous conditions will exist at upper elevations. Dense slabs of wind drifted snow could be easy for riders to trigger on slopes and features 35 degrees and steeper. Avalanches could break within layers of new and wind drifted snow, or on variable old snow surfaces buried Thursday (3/18). Seek out small slopes to test the new snow before committing to consequential routes. Watch for cracking, collapsing, and recent avalanche activity. Avoid steep unsupported slopes and start zones with signs of wind drifted snow, especially areas below cornices.

    (3/8/2021) Example photo of a small natural wind slab on Wright Mountain in the Snoqualmie Pass Zone. The slab broke near the base of cliffs and the cornice above serves as an indicator of the wind-loaded slope below. [Photo: Trevor Kostanich]

Avalanche Discussion

Winter weather has returned and will continue through the weekend. Avalanche danger will increase as you climb up in elevation and transition into wind-affected terrain. Recent storm snow sits atop variable old snow surfaces: firm crusts on the southerly slopes, light faceted powder on the northerly slopes, and breakable crusts on the west and east slopes.  Avalanche conditions may change significantly depending upon what aspect and elevation you are on. Of most concern are north through east facing slopes above 4000ft. In non-wind loaded areas and at lower elevations, new snow will likely bond well to old snow surfaces. Carefully assess the new snow and watch for sudden changes in snow surface texture and hardness. Bring a conservative mindset and ease into terrain slowly gathering plenty of information along the way. 

In addition to wind drifted snow, keep cornices in mind as these already large features will continue to grow over the weekend. They could drop onto slopes below acting as huge triggers. Stand back from cornices along ridgelines and minimize overhead exposure to these features. Several large glide cracks and a few glide avalanches were observed recently as well. Cooling temperatures should limit glide activity for now, but these avalanches are difficult to predict. If you notice crevasse-like cracks in the snowpack, avoid these slopes and areas below. 

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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