Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Actively blowing snow will make wind-loaded features you want to avoid quite obvious. However, older slabs from Sunday may linger on some windward aspects. So, avoid all steep open areas where you find slightly firmer and thicker slabs of snow.

Problemas de aludes

  • Wind Slabs

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

    You may need to manage two versions of the same avalanche problem Monday. Increasing E-SE winds will start to form new slabs in some odd locations. During last week’s similar E-SE wind event, several backcountry travelers were surprised when they triggered wind slabs and a few even took unexpected rides. Fortunately, blowing snow and active drifting should make these new wind slabs easier to spot and avoid. Since they are fresh, you may find the trigger easily and run quickly on firmer snow below. 

    It could be trickier to identify older slabs that formed during the storm Sunday. Some of these may even sit on slopes being stripped by the wind. Larger cornices, textured surfaces, and firmer deeper deposits of snow can help you anticipate these older slabs. While they might be harder to trigger, they cloud produce larger slides that may even break above you. Be particularly vigilant for these sneaky old slabs in rocky complex terrain near cliffs and chutes.

    (2/25/2023)

    Natrual and human triggered wind slabs  the N Slope of Chair Peak from the past week's E-SE wind event.

    Photo: Dallas Glass

  • Loose Dry

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

    We don’t often talk about sluffs as a problem, but in this particular case, we feel you may easily trigger loose dry or very soft slab avalanches that run quickly. Some of these slides could even travel far downslope over a firm bed surface. Don’t let one of these smaller softer slides catch you by surprise and take you for a ride higher consequence terrain.

    (2/13/2023)

    A small loose avalanche triggered by snow shedding from trees.

    Photo: Dallas Glass

Avalanche Discussion

Increasing winds and a few inches of additional snow Monday could mean you see the greatest avalanche danger in the afternoon.

As of 5pm Sunday, the Pass has received 6-8 in of new snow. Avalanche professionals reported generally poor bonding to the old surface with some short shooting cracks in wind-affected areas. Alpental Patrol triggered shallow slabs 4-10 in deep during mitigation efforts. Many of these slides ran on a firm crust below. 

Prior to the storm variable snow surfaces existed around the Pass. This included firm icy slopes, wind-textured snow, soft powder, and weak sugar facets. This could cause the snow to respond differently from one slope to the next. Right now we expect avalanche activity to remain at or above the new/old interface. 

An easterly (E-SE) wind event on Thursday resulted in several natural and numerous human-triggered avalanches (2/23-24) up to size D2.5. While most of these avalanches were small, they often triggered easily. One slide caught a traveler and carried him over a large cliff where he sustain significant injuries requiring a helicopter evacuation.

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