Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A natural avalanche cycle may occur Saturday night. Heavy precipitation along with strong winds have created dangerous conditions. You could trigger a large and deadly avalanche on weak, old snow several feet deep. Steer around steep open slopes as well as sparsely treed terrain at mid-elevations while storms continue to stress these deep weak layers.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Heavy snow with strong winds are creating thick slabs. Look for shooting cracks and other signs of instability such as whumphing collapses. The new snow may feel 'right side up' as the storm winds down with a cooling trend, but with a number of potential weak layers, it will be best to give the snowpack a few more days before targeting steep slopes. In areas exposed to the wind, feel for firm or hollow sounding snow and generally avoid open slopes steeper than 35 degrees above treeline. Firmer slabs may form on a variety of aspects and further downslope than usual due to the strength of the winds. Cornices may easily break off and may trigger avalanches on the slopes below. 

    Public observations (thank you!) report shallow wind slabs releasing near Mission Ridge, and Salmon la Sac on NYE.  These avalanches may only be deeper and wider on Sunday.

    (12/31/2020) Wind textured snow in Mission Ridge area

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Heads up, persistent slab avalanches may begin to 'wake up' after this heavy storm load. A weak layer of sugary snow sits atop an icy crust from early December. Keep your distance from slopes 35 degrees and steeper that are open enough and tall enough to produce large avalanches. 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 the storms continue to stress these deep weak layers. The most dangerous slopes will be steep, open starting zones. Mid elevation, unsuspecting slopes in sparse trees are candidates for these deep avalanches as well.

    Weak snow above a crust is a tricky and historically deadly weak layer east of the crest. This structure may be anywhere from 1.5ft to 3+ft below the surface, above roughly 5,000ft. In the southern half of the zone, weak snow above the 12/21 crust is suspect with this additional storm, and may have been the interface for a ski triggered avalanche in the Salmon la Sac area on NYE. In the northern half, weak snow above a crust from early December is more concerning, as the 12/21 crust did not form there. In the Wenatchee Mountains, there is growing potential for avalanches to run on the ground.   

    (12/23/2020) A crown of an avalanche that ran between Dec 19-20th on a NE aspect near 7,000ft in the Alpine Lakes Wilderness.

Avalanche Discussion

There is quite a bit of uncertainty with potential for deeper weak layers as the storm cycle continues. Shallow wind slabs were triggered in different parts of the zone on 12/31.  Many lower and mid-elevation stations pushed above freezing on Friday with generally light precipitation. 

As is typical for the eastern slopes, there is a lot of variability in snowpack depth. Just east of the crest you may find 6ft of snow at 6000ft, but at that same elevation east of Highway 97 in the Wenatchee Mountains, you may only find a few feet of snow on the ground. 

Happy New Year from the Northwest Avalanche Center!  We hope you have a safe and healthy start to 2021. 

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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