Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Yet another round of snow will maintain dangerous avalanche conditions on Saturday. You can trigger large and potentially deadly avalanches on any open slope greater than 35 degrees. Expect deeper avalanches at mid and upper elevations and on wind loaded slopes.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Storms continue to pummel the Pacific Northwest, and Friday night’s system looks mild and wet. You could find more than a foot of new snow in some locations by Saturday morning and possibly the debris piles from an overnight natural avalanche cycle. These stormy conditions combined with the potential for natural avalanches should tell you much of what you need to know for traveling Saturday; this is a day to dial it back. Anticipate the most dangerous conditions during the morning hours while the snowpack adjusts to the new load. With all the recent snow, any avalanche may become large and deadly. Steer around all open slopes greater than 35 degrees and don’t linger in places where avalanche may run or stop. If you continue to observe active wind loading, you could see natural avalanche activity continue during the day. 

    We’ve been talking about buried persistent weak layers of facets and surface hoar in the upper snowpack for the past several days. On Friday, Crystal Mt Ski Patrol reported triggered avalanches failing on small facets several inches above the prominent 12/09 crust. So far, no avalanche activity has been confirmed on this layer in the backcountry. Now, this layer lies several feet below the snow surface. Any avalanche failing on these persistent grains would likely result in a very large and destructive slide. If you dig a snow profile you may find facets or buried surface hoar about 4” (10cm) above the 12/09. They seem to be most prevent on W-N-SE asepcts near treeline.

    (12/16/2020) Skin track test showing cracking in the surface snow. This can indicate storm slabs are present.

Avalanche Discussion

It’s been a wild wet week full of storms that continue to add to the snowpack. Now the most prominent snowpack marker (12/09 crust) lies 15-35” (40-90cm) below the snow surface. The bulk of our next system is expected overnight Friday into very early Saturday morning. During this time some locations like Paradise could see very dangerous avalanche conditions and natural avalanche cycles. By Saturday morning, the bulk of the precipitation should have passed and the avalanche danger on a slow decline. In areas that receive less new snow, locally lower avalanche hazard may exist. 

A second warmer and wetter system will arrive Friday evening. Expect avalanche conditions to rise again overnight possibly resulting in a widespread and very dangerous avalanche cycle. Travel in the backcountry Saturday night is not recommended. 

At the lowest elevations, the snowpack continues to get beat by warm temperature and rain. Anticipate thin snow coverage and challenging travel conditions. 

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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