Lawinenlagebericht

Stevens Pass

Northwest Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
4 · Gross
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Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Heavy snow and strong winds are expected to tip the scales and create a natural avalanche cycle. Very dangerous avalanche conditions are expected to peak Saturday afternoon, so travel into places where avalanches can start, run, and stop is strongly advised against. You could easily trigger deep and destructive avalanches on an old, slick crust.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1–2

    Heavy snowfall along with fluctuating temperatures and very strong wind are expected. It doesn't take a rocket scientist to tell us that conditions will be prime for avalanches on Saturday. Stay aware as you travel through snow and take notice if you see shooting cracks or recent soft avalanches. The new snow will sit over a variety of weak surfaces and older weak layers. Any small avalanche in the new snow could step down to be deeper and surprising avalanches. Strong wind will also redistribute snow in exposed terrain and create wind slabs, even below treeline. For these reasons, avoid slopes that are steeper than 30 degrees and stay out from underneath avalanche terrain.

    Example storm slab on a small test slope.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    3

    Heavy snow and strong wind will continue to tip the snowpack to its breaking point on Saturday, and you could trigger deep, wide and surprising avalanches. On Friday, a number of large and wide natural, and human-triggered avalanches ran on weak snow over the crust from mid-January. Some were triggered from a distance by skiers walking on a ridgeline or in adjacent terrain with huge whumphs reported. On Saturday, these could be 3ft+ deep and could be triggered from a distance or from below on connected slopes. Some slopes may have the ability to create these large and surprising avalanches, while other ones may not. The tricky part is that it will be very difficult to tell, and it's not worth betting your life on it. When the snowpack is this complex, keep your terrain choices simple and stay out of avalanche terrain. Elevations below 4,500ft may offer lower chances of triggering one of these. 

    (2/5/2021) This avalanche was remotely triggered in backcountry terrain just outside of the Crystal ski area. Similar to other recent slides, it failed on facets just above the 1/13 crust. 60cm deep, 150' wide. 5200' ESE aspect. Photo: Crystal Mt Ski Patrol

Avalanche Discussion

Josh Hirshberg reported a natural, 1,000+ft wide D2.5 persistent slab in Highlands Bowl (SE at 5,600ft) on Friday. Professional guides reported huge collapses (whumphs) below Skyline Lake. Ski Patrol at the pass remotely triggered 2ft deep avalanches while skinning on a ridgeline. These were on northeast aspects at 5,800ft and ran on the crust from 1/13. WSDOT triggered large avalanches in both new snow, and older snow early in the morning as well. One was a D3 avalanche (big enough to destroy some trees) and ran on the crust as well. These are the first confirmed avalanches on this layer that we have in the zone, and they are certainly not the last. 

The next round of snowfall should continue the current avalanche cycle, and we could see some defined avalanche paths run close to their full potential on Saturday into Saturday night. During the week, we observed sudden, planer, and often easy failures with snowpit tests in the upper pack. Others reported spooky collapsing. Even in some areas below treeline, we can't write off the chances for slabs to run on this deeper layer.

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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