Bulletin d’avalanche

East Slopes North

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 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You can trigger small loose wet and loose dry avalanches on very steep slopes. Small wind slabs can also be triggered on exposed terrain above treeline. Steer around thickly wind-loaded areas on steep slopes, and ride carefully in steeper terrain knowing that loose avalanches could entrain to become larger.

Problèmes avalancheux

  • Loose Wet

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

    Warming temperatures and sunshine will initiate another round of loose wet avalanches on very steep slopes facing the sun. Look for signs of loose wet activity such as rollerballs, and other small fan-shaped avalanches as the daytime warms. The potential size of loose wet slides will increase where you find more new snow, such as areas closer to the crest. Don't let these predictable avalanches catch you by surprise in or around terrain traps or extreme terrain.

    Loose dry avalanches are possible on very steep slopes in the shade. Ride cautiously in steeper terrain knowing that you could initiate sluffs that may entrain loose snow and grow larger.

    Example small loose wet slides from earlier this season.

  • Wind Slabs

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

    Moderate westerly winds transported the new snow onto lee slopes near ridgelines. The potential size of wind slabs may increase at the highest elevations, and near the Cascade crest where more recent snow fell. Look for signs of instability such as shooting cracks, and stiffer textured snow over weaker snow. Feel for textured wind-affected snow as you change aspect and elevation. For the most part, avalanche activity should be shallow, and confined to the new snow.

    If traveling along ridgelines with large cornices make sure to stay well away from the edge. Cornices could fracture and trigger shallow slab avalanches. Travelers are surprised every season when cornices break further back than they expect. If you see glide cracks, stay well out from underneath them. Glide avalanches are notoriously difficult to predict and can be destructive when they release. 

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

Avalanche Discussion

Around 5" of snow was observed on Wednesday in the Cutthroat drainage, with accumulations beginning at around 5,000ft and above. Shallow wind drifts were observed near ridgetops, and small loose dry avalanches were easily triggered on slopes steeper than 40 degrees. The new snow fell on a recently buried sun crust on all aspects but direct north. On northerly and shaded aspects, observers were still reporting cold dry snow above about 6500' in elevation. An observer also reported a large recent glide avalanche in Cutthroat at around 5,400ft that appeared to have occurred since March 21st.

Since the beginning of March, the region has undergone a slow warming trend and now steady but cool temperatures. Observers have reported loose avalanches (both wet and dry) and falling cornices.  Cornices are very large and still loom on many ridges.  Most of the observations of cornice fall came early in the month, but we continue to receive occasional reports. The mid-January weak layer that plagued most of the Cascades for the month of February has not been a major concern near Washington Pass.

Régions couvertes