Lawinenlagebericht

East Slopes North

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

An up-slope storm will add to dangerous conditions in the area. Large storm slabs and loose dry avalanches are likely on steep slopes during the day. The storm should continue to slowly stress deeper weak layers in the eastern edge of the zone, and areas with a  shallow snowpack. Steer around steep open slopes as well as unsupported terrain at mid-elevations during times of heavy snowfall.

Lawinenprobleme

  • Storm Slabs

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

    Folks reported about 15" of new snow in the Cutthroad Drainage on Sunday. Another 10" or so may fall on Monday. 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 or whumphing collapses. 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 Monday. 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. 

     

    (1/2/2021) Storm slab in nearby East Central Zone.

  • Persistent Slabs

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

    Heads up, persistent slab avalanches may begin to react during this prolonged storm event. 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, and may not be a problem anymore. 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 Sunday, an observer reported an isolated whumph near a windloaded ridgeline at 6,800ft in the Cutthroat Drainage. A observer in the Twisp River found ongoing wind transport in the alpine throughout the day. Digging down on a SW aspect at 5,800ft, he got sudden collapse test results down 75cm on the Early December Crust. Other recent snowpack tests showed that propagation was possible on this 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 these 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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