Bulletin d’avalanche

East Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

Sat
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 may be able to trigger avalanches in wind drifted snow at upper elevations. Forecasted snow and wind may elevate the danger in the northern portion of the zone by the end of the day. Assess wind-exposed terrain carefully before committing to steep slopes. 

Problèmes avalancheux

  • Wind Slabs

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

    Continued moderate and gusty winds have developed wind slabs on lee aspects near ridges. Much of the available snow from windward aspects have already been scoured by the winds, and without significant snow in the forecast, new wind slab development will likely be minimal.  However, you may still be able to trigger lingering wind slabs, particularly at upper elevations. While these are most likely a problem on E aspects, terrain features can heavily influence wind direction, and you may find stiff wind drifted slabs on all aspects. Look for signs of wind drifted snow that feels hollow or looks pillow-like. You can also use visual clues such as cornice direction or drifts around rocks and trees to indicate wind direction. If you feel the snowpack collapse or observe shooting cracks in wind-exposed terrain, you should steer around recent drifts and slabs on slopes steeper than 35 degrees. Wind slabs may have formed over weak faceted grains in some locations. Avalanches triggered on these weak layers tend to break farther or wider than anticipated. Use extra caution in sheltered terrain near the crest on NW-NE aspects. There is uncertainty about the distribution and extent of this layer, but it is only 1-2ft deep, so you can dig down to identify these layers quickly as you move through the terrain. If you find weak, sugary snow over firm melt-freeze crust under a cohesive slab, you could trigger surprising avalanches on steep slopes.

    (2/1/2022)

    Shooting crack on a wind-loaded feature at 5,800ft in the upper Salmon la Sac drainage.

    Photo: Ryan Minton

Avalanche Discussion

Beneath the storm snow on sheltered areas on north and east aspects, facets over a crust have been observed at mid-elevations. This layer seemed inconsistent in distribution and may not exist in wind-exposed terrain. Where this layer was observed, the facets were generally small and unreactive. However, reports of collapsing on a similar layer in the Stevens Pass zone are notable, and it is important to track this interface as you enter new terrain. NWAC observer Drew found this crust/facet combo out at Holden, but there isn't enough snow on it to be problematic yet. This will be a layer to monitor as we get additional snow. Where there was no faceted snow at the interface, observations throughout the zone have found the storm snow to be well-bonded to the crust layers. New snow amounts are minimal in the eastern portion of the zone, and avalanche danger is isolated to shallow wind slabs near the leeward sides of ridges. 

There is a slight chance of sun breaks tomorrow. If you find yourself on steep southern aspects that are warming in the sun, you may be able to trigger wet loose avalanches. 

Régions couvertes