Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Dangerous avalanche conditions continue after a long period of heavy snow, rain, and strong wind near and above treeline.  Avoid being on, under, or near slopes 35 degrees and steeper at mid and upper elevations where you can trigger dangerous persistent slab avalanches. Small avalanches in surface snow are possible below treeline.

Avalanche problems

  • Persistent Slabs

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

    Persistent slab avalanches could be very large and could bury or kill you. These dangerous and surprising avalanches can catch even the most experienced backcountry travelers. With uncertainty about how easily you can trigger these avalanches, it's important to give them some time to heal. You may be able to trigger these avalanches from long distances away. The best way to stay safe is to avoid where these avalanches exist. Keep your distance from slopes 35 degrees and steeper that are open enough and tall enough to produce large avalanches. Make sure you're not standing below or adjacent to steeper slopes. Use clues to stay out of avalanche paths, like trees stripped of uphill branches or openings in vegetation that run up slopes. Watch for obvious signs of instability like recent avalanches, whumphing collapses, or cracks shooting through the snow.

    Persistent slabs are more likely closer to the Cascade crest, in the western half of the zone. The most dangerous slopes will be at the highest elevations, where snow stayed mostly dry and where southwest to west wind drifted snow over the past few days. Avoid any areas that appear to be covered with thickly drifts snow. You can find a thin weak layer of small facets (and in places surface hoar) above a crust buried about 1.5-3 feet below the surface. Further east, and in the Wenatchee mountains, there's not enough snow over the weak layer to be a problem.

    (12/18/2020) Part of a D2 persistent slab avalanche that was ~500ft wide and 15"-20" deep in neighboring Stevens Pass zone. The avalanche was unintentionally and remotely triggered by experienced backcountry skiers on 12/17. The avalanche ran on weak snow over the 12/9 crust.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Watch for triggering avalanches in recent storm snow. Cold snow will fall with cooling temperatures on Monday night. Following travel advice for the Persistent Slab avalanches will keep you from triggering avalanches in the storm snow as well. At upper elevations, this new snow may be drifted and adding stress to the underlying weak layer. In addition, you may be able to trigger small avalanches on lower elevation slopes. At the lowest elevations, you may find heavy wet snow that has yet to freeze. 

Avalanche Discussion

Observations have been limited in the zone in the past 5 days. There is a lot of variability in snowpack depth just east of the crest where you may find 6ft of snow at 6000ft, but east of Highway 97 in the Wenatchee mountains you may only find a few feet at the same elevation.  In adjacent zones, a prolonged cycle of widespread avalanches occurred from the 18-21st. The December 9th crust is a prominent snowpack marker, and can be found at all elevations up to around 7000ft. Above this layer lies two potential layers of concern, a layer of facets just above the crust, and a thin layer of surface hoar a few inches above that. 

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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