Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Stormy weather will continue to drive dangerous avalanche conditions Sunday as rain, wind, and new snow stress the snowpack. Dial back your terrain choices and stay off all open slopes greater than 35 degrees.

Lawinenprobleme

  • Loose Wet

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

    Heavy snowfall will transition to rain Saturday night as snow levels rise to 5000ft. Expect natural and triggered wet avalanches in all elevation bands. The greatest wet avalanche hazard will exist overnight before temperatures cool again Sunday afternoon (3500ft snow levels). Avoid steep slopes during periods of heavy rain. Wet loose avalanches could entrain significant snow and grow large.  Glide avalanches are not out of the question either, especially in areas where shallow snow covers smooth rock. Choose conservative terrain away from large open slopes where you encounter a wet and unconsolidated snowpack. 

    Example photo of large wet loose avalanches on Table Mountain earlier this December.

  • Storm Slabs

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

    The snowpack still needs time to adjust to the 4ft+ of storm snow received over the past week. You can trigger large avalanches within recent snow on open slopes greater than 35 degrees at mid and upper elevations. Expect the most dangerous conditions above the rain line (5000ft) where significantly more snow will accumulate overnight Saturday. The thickest and most reactive slabs will exist in wind loaded alpine terrain. Sunday won't be a day to linger in areas where avalanches can run or stop. Use small slope tests and hand pits to observe the recent snow and determine which layers might fail.

    Recent avalanche activity produced crowns up to 3ft deep, although the majority of avalanches have been shallower involving the most recent 24hr storm snow.  On Wednesday, a skier triggered and was partially buried in an avalanche outside the Mt Baker Ski Area boundary, along with human triggered avalanches reported each day since. While we think that older weaker snow above the crust and older storm layers are showing signs of healing, incoming snow each day continues to stress the snowpack, create new storm snow instabilities, and drive dangerous avalanche conditions.

    (12/16/20) Snowboarder triggered avalanche (D2) on a northwest aspect near 4500ft on Grouse Ridge in the Glacier Creek area. Crown height up to 18in. Photo Tristan Demers

Avalanche Discussion

It’s been a wild week full of storms that continue to add to the snowpack. Saturday night and Sunday will be the wettest yet, with snow, wind, and rain creating rapid change. The snow conditions and avalanche problems will be very different at low and high elevations. Be prepared to make observations as you travel and choose lower angle terrain if you see recent avalanches, or experience shooting cracks or collapses. In areas where you find a firm and frozen crust at the surface, avalanches will be unlikely. 

In nearby zones (Stevens Pass, East North/Central) weak persistent grains formed and were buried over the past week. A high degree of uncertainty exists surrounding this potential layer in the West Central. If you dig a snow profile, look for small sugary facets or feathery surface hoar about 4” (10cm) above the prominent 12/09 crust. If you travel at mid and upper elevations, consider limiting your exposure to large avalanche terrain where this layer might live. 

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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