Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

In exposed locations near ridgelines at upper elevations, you may be able to trigger avalanches where strong winds drifted snow into thick slabs during the recent storm. Approach ridges in alpine areas slowly and avoid steep slopes if the snow feels stiff or sounds hollow. Exposed rocks, stumps, and other hazards can increase the consequences of being caught in even a small avalanche.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Ridgeline winds during Saturday's storm were sustained in the 30mph range with gusts to 50-60mph. While the brunt of the storm is over, you may still be able to trigger lingering slab avalanches where the winds deposited snow into deep drifts. Since many areas still have a thin snowpack, you will most likely encounter these unstable slabs on steep ridgelines with little vegetation or trees. Use visual clues such as cornices, textured surfaces, or wind drifts to identify wind loaded terrain. Watch for signs of instability, such as cracks shooting out from your skis or rounded pillows of snow that sound hollow. Steer around steep slopes that show these signs of wind loading. 

    (11/23/2022)

    The small drifts of snow behind these trees and shrubs give you a good indication of the wind direction, right to left, in this photo.

    Photo: Katie Warren

Avalanche Discussion

Access to many areas of the eastern Cascades is challenging, and we have limited information about the snowpack. Despite the recent storm, access is still challenging. If you are headed out into the mountains this weekend, be prepared for long approaches on nearly bare ground. Many motorized trailheads have limited snowpack, and most have yet to begin grooming operations. New snow may shallowly bury rocks, stumps, creeks, or other hazards at upper elevations. 

Prolonged, cold, dry weather in mid-November transformed snow into weak, angular, sugary snow crystals. We received observations of surface hoar growth and weak snow in the Mt. Aix and Darland Mountain areas. This weak layer may now be buried up to 15" in some locations. This past week's warm temperatures have helped to strengthen and round these snow grains, and an NWAC forecaster found a strong and well settled snowpack at nearby Crystal Mountain. However, we still have some uncertainty about the extent and distribution of this weak snow layer. When traveling on sheltered northern aspects, it is important to dig down and determine if this persistent weak layer exists beneath the new snow. Avoid traveling on steep terrain if you find a weak sugary layer of snow or feel the snowpack collapse beneath you. 

If you are out and about in the mountains, let us know what you find by submitting an observation.

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