Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Recent winds from all directions have created slabs that remain possible to trigger. Look, listen, and feel for signs of instability such as shooting cracks and whumphing collapses as you travel. Continue to treat firm or hollow sounding snow with respect while on steep slopes.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Wind slabs can be found on all aspects, and in pockety distribution at all elevations. Wind slabs may be triggered by surprise, as they may rest over a layer of weak snow. Prior to the last storm, weak surfaces and surface hoar were widely distributed in the zone. Any recent slabs may continue to be reactive longer than you may think because of it. Wind slabs may become more connected and thicker as you ascend in elevation. Use surface textures and cornice formation as visual clues where slabs may be. Hollow sounding and firm or textured snow are other clues that wind transport has created slabs. 

    Look for signs of instability such as shooting cracks and whumphing as you travel.  If you see these signs of instability, dial back your terrain choices and stay off of steep features. In this case, be sure to avoid the obvious steep, wind loaded slopes, but also take into account cross-loaded and steep midslope features. This is also a good time to dig lots of quick pits, looking for a thin grey stripe of buried surface hoar and to check how the recent snow is bonding. 

    (12/2/2020) Easterly winds continued to load NW aspects at the top of the Swath's start zone on Tuesday.

Avalanche Discussion

Observers in the western edge of the zone noticed plumes from ridgelines that indicated wind transported snow from south and east winds. Wind slabs were resting on a variety of surfaces, and although no avalanches were triggered, the structure of strong snow over weak snow existed. On Sunday, I found widespread surface hoar in the North Fork of the Teanaway on all aspects above 5000'. Other observers found surface hoar in places like the Chiwaukum Range as well. 

On steep south facing slopes, the sun may warm the snow enough to create small wet loose slides in the middle of the day. Be sure to get off of these slopes if you notice wet sticky surfaces, or rollerballs. 

Snowpack height and coverage varies significantly across the area. Areas near the cascade crest have a substantially deeper snowpack than low elevations and further east. Use the weather stations to check how much snow is on the ground in various locations. 

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.

Régions couvertes