Boletín de aludes

East Slopes Central

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

7:00am Update: Precipitation numbers underproduced overnight, leading to overall slightly lower danger. 

Strong southeasterly winds and a storm favoring the eastern slopes of the cascades will build unstable slabs of wind drifted snow. These are likely to form beneath ridges, on mid-slope convexities, and at the base of cliffs. Avoid steep wind-exposed terrain at higher elevations and steer clear of stiff pillow-like drifts on steep slopes. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    A storm favoring the eastern slopes of the Cascades will likely bring significant winds and snow accumulations to locations further east, like Mission Ridge. There are various weak surfaces with faceted snow and surface hoar and surface crusts at lower elevations and southern aspects. This could make for tricky conditions, small storm slabs may form over weak surfaces, and adjacent slopes with slightly different aspects may have variable stability.The most concerning locations will be where the wind drifts snow into deep, stiff wind slabs. 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. While you should anticipate finding wind slabs below treeline on sparsely vegetated slopes, they will likely be larger and more dangerous in exposed terrain as you climb in elevation. Avoid steep slopes beneath ridgelines, cols, and other open, exposed slopes. Look for textured surfaces and active transport to identify potentially wind-loaded terrain. If you observe red flag signs of instability, such as shooting cracks within wind stiffened snow, avoid steep slopes or move to more sheltered areas. 

    (1/2/2023)

    Small, ski triggered hard slab avalanche near Crystal Mountain. 

    Photo: Barrett Gray

Avalanche Discussion

While there is some uncertainty with this incoming storm's snow totals, the forecast favors the eastern Cascades, and we could get up to 1ft of new snow in some locations. Surfaces vary widely with aspect and elevation. Southern slopes and lower elevations have a breakable melt freeze crust, upper elevations have a 3-4inch wind stiffened layer of snow, and northern sheltered aspects have soft, weakening storm snow. Large, feathery surface hoar crystals now cover these surfaces. Inconsistent old snow surfaces often lead to a widely variably bond with the new snow. While wind slabs will be the primary hazard due to their larger size, you could see reactive storm slabs in sheltered terrain at lower elevations. Thursday will be a good day to pay close attention to how the snow reacts as you travel. Use quick hand pits to observe how well the new snow bonds. Small test slopes are also a great way to see if you can get the new snow to slide. If either of these informal tests shows new snow sliding easily, dial back your terrain to low angle slopes. A slight increase in temperatures on Thursday could bring rain to lower elevations trailheads, be watchful for small wet loose avalanches running on the Christmas Crust.

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