Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

You should avoid traveling in and around any avalanche terrain on Thursday, as a powerful winter storm will create very dangerous avalanche conditions. A widespread natural avalanche cycle will occur, and avalanches may happen in unusual locations. Even lowland areas with consistent snow may see avalanches on steep terrain features and snow may slide from roofs of buildings.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Certain
    Taille
    2–3

    Heavy snowfall with warming temperatures and a weaker than average Pacific Northwest snowpack set us up for a very widespread avalanche cycle. Large natural storm slab avalanches will occur at all elevations, and some may be large enough to run through lower elevation bands. There is potential for these avalanches to run on crusts and weak layers deeply buried in the snowpack. In areas of the Wenatchee Mountains with a thinner snowpack, avalanches may run to the ground. 

    Mission Ridge may see impressive snow accumulations, up to 2.5 inches precipitation forecasted to fall as snow, which is unusual for areas that far east of the Cascade Crest. Areas closer to the crest may pick up nearly 4 inches of water.  With this much new snow, even avalanches within the storm snow could be very large. Thursday is a good day to avoid the mountains altogether. 

    (1/12/2021) Expect storm slabs like these to be widespread and larger in many areas on Thursday. 

    Photo: Josh Hirshberg

Avalanche Discussion

Thursday is not your typical high avalanche danger day. While snowpack depths may limit the distribution for very large avalanches, if the terrain and snow depth align, we will see very large avalanches. 

Precipitation rates will peak overnight on Wednesday, followed by warming temperatures on Thursday morning and increasing winds. This rapidly changing weather will create a mixed bag of unstable snow, all of which will likely produce avalanches large enough to bury or kill you. In addition, there is a chance of mixed precipitation and ice accumulation, creating a different but significant hazard for travel. 

Shuksan Arm, the Chair Peak basin, and Mt. Mastiff have all had avalanches on deeply buried weak layers in the snowpack. And Mission Ridge Patrol reported that an explosive triggered slab stepped down to the Solstice crust. These layers will be the likely culprits to any very large avalanches on Thursday.

Régions couvertes