Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

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

With heavy snowfall and strong winds, avalanches may run naturally on Saturday night. Dangerous conditions will continue into Sunday. At mid elevations and in the eastern edge of the zone, you could trigger a deeper persistent slab avalanche.  Steer around steep open slopes as well as unsupported terrain at mid-elevations while the snowpack adjusts to this hefty new load. 

Lawinenprobleme

  • Storm Slabs

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

    If the weather forecast holds, we could have over 15" of new snow at Washington Pass by Sunday. Steer around steep slopes while the snowpack adjusts to this hefty new load. You could trigger a large slab avalanche within the recent storm layers. Slabs could be deeper and thickened by wind at mid and upper elevations. Firmer slabs may form on a variety of aspects, and further downslope due to strong winds. Look for signs of instability such as shooting cracks. Places such as steep, convex rollovers and unsupported slopes will be the easiest places to trigger a slab within the new snow. At mid-elevations and further east, storm slabs have the potential to step down to deeper weak layers.

    Loose dry avalanches may run easily on Sunday. Look for these fan-shaped slides that start from a point (also known as point releases). In big, steep terrain these could entrain lots of snow, and create large avalanches. 

     

    (12/31/2020) Look for shooting cracks in new or wind drifted snow as a sign that you can trigger a slab avalanche.

  • Persistent Slabs

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

    Heads up, persistent slab avalanches may begin to react after this heavy storm load. A weak layer of sugary snow sits atop, or below a thin icy crust from early December. Keep this deeper layer at the top of your mind at mid elevations and further east where the snowpack is more shallow. In most areas near the crest, this layer has already undergone a substantial avalanche cycle. Watch for obvious signs of instability like recent avalanches, whumphing collapses, or cracks shooting through the snow. The next couple of days will be a good time to stay off of steep, open slopes as storms continue to stress these deep weak layers. The most dangerous slopes will be mid elevation, unsuspecting slopes in sparse trees, and large open starting zones in the eastern edge of the zone.

    (12/31/2020) Orange lines outline crowns and debris from a very large (+D2.5) slab avalanche that occurred during a widespread avalanche cycle on Dec 21st. The red line shows a small slab avalanche that occurred this week, as loose snow pouring off the cliffs triggered recently drifted slabs about a foot below the surface. NE, 6500-6700ft, West Fork of the Methow River. Photo Josh Hirshberg.

Avalanche Discussion

On the 1st, an observer reported shooting cracks and 10-12" deep storm slabs in Cutthroat Drainage. Some recent snowpack tests showed that propagation was still possible on the early Dec weak snow/crust interface about 2 ft down at around 5700' on Driveway Butte.  This storm should produce significant accumulations for the East North zone, and may stress deeper weak layers.  

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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