Bulletin d’avalanche

East Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Wed
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

Loose avalanches can run on any steep slope receiving direct sun.  You are most likely to trigger a wind slab near ridgelines or below terrain features like cliff bands.  Within the zone, the hazard will highest near the Cascade crest and lowest further east and at lower elevations. 

Problèmes avalancheux

  • Loose Wet

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

    Following several cool cloudy days with light snowfall,  wet loose avalanches will be ready to go with some spring sunshine and a bump in freezing levels. If you see rollerballs or pinwheels release naturally on very steep sunny slopes or below rock faces, it's time to change aspect or move to lower angle terrain.  There's a chance that high clouds could dampen the sun's impact, so keep an eye on how sky conditions change throughout the day. 

    Loose dry avalanches are possible on very steep slopes in northerly or shaded terrain.  Don't let either type of loose avalanche catch you by surprise around terrain traps.   

    Example natural wet loose avalanche and roller ball activity below rocky terrain in the neighboring West North zone. Photo: Zach McGill

  • Wind Slabs

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

    Recently formed wind slabs are likely to be found at upper elevations and on the lee side of ridgelines and below cliffs bands where spindrifts have deposited recent snowfall.  As you travel, feel for textured wind-affected snow as you change aspect and elevation.   Wind slabs may be easier to trigger on northerly aspects where they built over weaker, older snow.  They are more likely to have formed in the western part of the zone where more snow has recently accumulated.

    If traveling along ridgelines with large cornices make sure to stay well back from the edge.  Travelers are surprised every season when cornices break further back than they expect.  Cornice fall could trigger an avalanche on the slope below.

    Example from earlier this winter: A skier intentionally triggered a small wind slab avalanche on a SW aspect at 7400 ft near Washington Pass.

Avalanche Discussion

2-5" accumulated through Monday morning, with the highest totals likely west of Washington Pass with westerly ridgleine winds.  This builds on a few inches of snow received earlier in the weekend.  On southerly aspects, this new snow sits above the most recent sun-crust buried 3/18.  On northerly shaded aspects, observers were still reporting cold dry snow above about 6500' in elevation.  Below 5500', there is very little recent snow above the surface crust. 

Since the beginning of March, the region has undergone a slow warming trend. 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 was much less of a factor near Washington Pass.

Régions couvertes