Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

With moderate southeasterly winds and light snow in the forecast, you can expect to find shallow, unstable slabs of wind drifted snow. These will likely form beneath ridges and cliffs on opposite aspects as older slabs from earlier in the weak. Avoid these stiff pillow-like drifts where you find them in steep terrain.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    This storm is likely to favor the eastern slopes of the Cascades further south. However, the East North area may pick up 6-8" of new snow with moderate ridgeline winds. Be watchful for drifting and blowing snow near ridgelines, likely on different aspects than what we have been looking for over the last few days. You may also find these slabs forming beneath cliffs and cross-loaded rolls and gullies mid-slope in exposed terrain at upper elevations. Observations indicate widespread surface exists in many locations, and wind slabs forming on these weak feathery crystals could be quite reactive. Textured surfaces and blowing snow along ridgelines will be visual clues of wind slabs. Signs of instability, like shooting cracks in freshly drifted snow, will indicate which slopes to steer around. 

    Look for signs of blowing snow on the higher peaks and ridgelines to help identify which slopes are being loaded. 

    Photo: Katie Warren

    12/17/2022

Avalanche Discussion

 It has been about a week since several very large avalanches (D2.5-D3.5) failed on persistent grains buried early last month in the Washington Pass Area. These avalanches ran during the Christmas storm cycle (Dec 24-27th). Recent snow profiles suggest that recent natural avalanches involved the Dec 8th buried surface hoar layer (2-3ft below the surface and below the Christmas crust), with at least one avalanche suspected to have run on sugar-like facets from November deeper in the snowpack. A weak snowpack structure also exists in the Mazama environs and eastern foothills. The lack of recent avalanche activity and other signs of instability have increased our confidence that triggering a persistent slab would be unlikely. The amount of moisture coming in with this storm is probably too light to overload these deeply buried weak layers. However, there is some uncertainty with precipitation amounts, particularly in the foothills east of Mazama, where the potential for snowfall to exceed expectations exists. So make sure to heed warning signs such as large collapses, and stick to lower-angle terrain if you witness signs of instability. We will have to wait and see if future loading events bring these deep persistent problems back to the forefront. 

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