Lawinenlagebericht

Snoqualmie Pass

Northwest Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Recent large natural avalanches, multiple nights without a sold freeze, and very warm weather all point towards dangerous avalanche conditions. Plan when and where you travel to minimize the time spent in large and complex terrain. Destructive springtime avalanches may occur without warning especially during the heat of the day.

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2

    After 4 nights without a solid freeze, you could encounter large natural loose wet avalanches that entrain heavy snow and gouge as they descend. These aren’t your normal small surface loose wet slides. These are much bigger and more dangerous. Several feet of wet punchy snow sits on the surface of most slopes. On Saturday, as temperatures heat up, you may see this wet heavy snow start to slide down. Avalanches could originate from steep and rocky terrain above you and travel far downslope. Plan your day to avoid traveling below large avalanche paths particularly as temperatures rise. 

    Our primary concern comes from natural loose wet avalanches. However, you may trigger wet slides on steep slopes greater than 35 degrees. Whatever thin crust that forms overnight won’t last long in the warm and sunny weather. Once you sink past your ankle, seek out lower angled or more frozen snow.

    (4/11/2021) Example: Pay attention to slopes above you. They could produce large natural avalanches that travel down to your location.

  • Glide Cracks

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    A large natural glide avalanche occurred above the Alpental access road Thursday night. Similar large and even very large (D3) glide slabs released during this same timeframe across the Washington Cascades. One thing is for sure, water is moving in the snowpack, and in many instances reaching the ground. Continued hot weather will only exacerbate this problem over the weekend. Glide avalanches can release without warning any time of the night or day. Don’t linger underneath slopes where you see crevasse-like glide cracks.

    (4/16/2021) This natural glide avalanche occurred overnight above the Alpental access rd. 4/15-16/21: NE 3400'. WS-N-D2-G: Photo: Alpental Ski Patrol

Avalanche Discussion

The blue skies and warm temperatures make the mountains feel very inviting. However, we are deep into the most prolonged period of warm weather the snowpack has seen all year. This big change in the weather may produce big problems. Simple red flags like recent large avalanches, 4 nights above freezing, and temperatures possibly reaching into the 60s highlight this particular dangerous springtime period. While the danger rating and avalanche problem may feel very commonplace, we’re talking about the first major spring shed cycle of the year. 

We’ve chosen to emphasize loose wet and glide avalanches, but other springtime shed slides deserve mention. Wet slab avalanches fail when a layer of water pools within the snowpack. This could occur on any number of old weak layers, including the very deep mid-January interface that produced massive avalanches earlier this winter. Additionally, cornices may collapse during the hot weather. These could entrain snow below or trigger other avalanches. No matter what type of wet issue you encounter, the travel advice remains the same. If you choose to go into the mountains:

  •  Plan your day to travel and exit early. 
  • Give yourself plenty of options to adapt to rapidly changing conditions, including safe travel routes back to the trailhead. 
  • Pay attention to overhead slopes and choose routes that help you limit the time you spend underneath large and complex avalanche terrain. 

Daily avalanche forecasts will end on Sunday, April 18th.

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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