Boletín de aludes

East Slopes South

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Dangerous avalanche conditions will persist on Tuesday. It will be easy to trigger large avalanches, especially in areas where the wind has blown snow into deep drifts. Choose conservative terrain and avoid steep slopes if you experience shooting cracks, collapsing, or observe recent avalanches.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    As of Monday afternoon, the storm has tapered off, and we are getting a brief break in the heavy precipitation. But lingering snow showers and moderate winds will continue into Tuesday. With 1-2 feet of snow that accumulated on very weak surfaces, it will take time for the snowpack to adjust and storm instabilities to settle. You may no longer see widespread natural activity, but you can easily trigger avalanches in steep terrain at all elevations. If you are traveling near ridges or in areas where the wind has deposited snow, these avalanches may be larger and more dangerous. 

    Travel cautiously and avoid steep terrain, especially in areas with deep wind drifts. Use hand pits and small test slopes to observe how the new snow is bonding to the existing snow surfaces. Strong over weak layering that fails easily in hand pits or test slopes that produce shooting cracks or mini avalanches are all signs you should stick to low-angle terrain. 

    (12/23/2021)

    Small slopes can help you see how the new snow reacts under your weight. Shooting cracks are a good indication you should stick to low-angle slopes.

    Photo: Shane Robinson

Avalanche Discussion

Snow totals from Monday’s storm were impressive throughout the East South zone. Up to 2 feet of snow accumulated near the Cascade Crest and 16-17 inches in areas further East. A widespread natural avalanche cycle occurred during peak precipitation rates in the early morning hours of Monday. 

While observations in East South are limited, this new snow likely fell on a weak snow surface. Underlaying the older weak snow is a variety of surfaces, from sun crusts and wind crusts to soft snow. As a result, adjacent slopes and slight variations in aspect may react very differently to the new snow. We are particularly concerned about steep solar aspects with a few inches of preserved stellar snowflakes, surface hoar, and faceted crystals on a sun crust. On these slopes, avalanches may break farther and become larger than a typical storm slab. 

While most observations have indicated a good bond between the upper snowpack and the Solstice crust, now buried 2-3 feet below the surface, some surprising avalanches in other zones have occurred on this layer. Including an explosive triggered slab that stepped down to this layer during avalanche mitigation work at Mission Ridge on Monday. This uncertainty, along with the potentially high consequences of these very large avalanches, warrants extra caution as smaller avalanches may step down to deeper interfaces. 

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