Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
Voir sur la carte

Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
Open full map
Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Fresh wind slabs will develop through Thursday morning below ridgelines near the Cascade crest.  Steer around steep open slopes where you find freshly drifted snow.  In less wind-affected snow, rollerballs or small wet loose avalanches will run on very steep sunny slopes.  

Problèmes avalancheux

  • Wind Slabs

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

    New snow along with strong westerly winds Wednesday night and Thursday will build fresh wind slabs on lee open slopes near and above treeline.  Feel for wind-stiffened snow as you change aspect and elevation. Visual clues like blowing snow along ridgelines and spindrifts below steep cliffs can tip you off regarding which slopes are most suspect.  You can test the bond of the new snow to the old snow surface (likely a crust) on small test slopes before entering more consequential terrain. 

    (3/22/2021) Small wind slab release on a test slope. Notice the rippled texture to the snow surface. Photo: Matt Primomo

  • Loose Wet

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

    It's spring-time so any amount of sunshine following new snow means rollerballs and wet loose avalanches will run on very steep sunny slopes.  Switch to lower angle terrain or shadier slopes if find yourself sinking in more than ankle deep into wet snow.  Watch for rollerballs or natural small wet loose avalanches that release below rock faces as a signal that the chances of triggering a wet loose avalanche in increasing in similar terrain.  Avoid triggering even a small wet loose avalanche near terrain traps like cliff bands or gullies. 

    (3/30/2021) A small, skier triggered wet loose avalanche on a southeast facing slope at 6,300ft near Mission Ridge. Photo: Matt Primomo

Avalanche Discussion

4-8 inches of new snow near the Cascade crest will likely build over a crust (4/7) on most aspects and elevations.  Snowfall totals will be the highest downwind of the Puget Sound Convergence zone that forms later Wednesday night.  Much lower snowfall totals and avalanche danger is expected further east including near the Wenatchee Mountains.  Cooler temperatures will lower the chances of glide avalanches or cornice fall.  Keep an eye on open glide cracks and cornices as we head into next week when warmer weather returns. 

The lower snowpack is strong and well settled. A layer of facets above a crust from mid-January is about 2-6 feet below the surface. The layer has been dormant for a month although it may awaken later this spring with the right conditions.  

If you're out midweek let us and the backcountry community know what you see and Submit an Observation. 

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