Boletín de aludes

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Peligro de aludes

Fri
Alta montaña
4 · Fuerte
Límite del bosque
3 · Notable
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

You're very likely to trigger a large, destructive avalanche. Slides can be triggered from flat terrain a long distance from where they release. Smaller avalanches involving only the recent snowfall are also possible, especially on slopes receiving direct sun. These natural and triggered slides may break into the weak layers beneath, creating much larger, more destructive avalanches. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    2–3

    You're very likely to trigger a large, unsurvivable avalanche. Some of these slides will be powerful enough to destroy a house.  A week of heavy snowfall is stressing weak layers near the base of the snowpack. These layers of facets and/or surface hoar on shadier aspects and crust + facet combinations on sunnier slopes are incredibly fragile and can be found on most slopes.Multiple Persistent Slab avalanches were triggered in the past several days. Tuesday, The Sun Valley Ski Patrol ski-triggered a large avalanche in closed terrain. The slide was 2-4 ft thick, 100 ft wide, and broke branches during its 900 ft vertical run (photo at right/below). These avalanches can release in surprising ways. You can trigger them from flat or low-angle terrain long distances away from steep slopes. 

    (2/6/2024) The Sun Valley Ski Patrol ski-triggered this large avalanche Tuesday morning in the Cold Springs Chutes in the Sunrise Expansion Area. This area has not yet been opened to the public. It failed on a NE aspect near 8000'. The slide was 2-4 ft tall, 100 ft wide, and broke branches during its 900 ft vertical run. The debris piled up 4-7 feet deep against trees. Photo: Sun Valley Ski Patrol

  • Storm Slabs

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

    This zone picked picked up 2-4' of snow in the last week. Expect to find thick slabs of wind-drifted snow at upper elevation. These dunes, drifts, and pillows may be masked by light snowfall and could be hard to identify.  While less likely, slab avalanches are also possible on steep slopes that are sheltered from the wind. Cracks shooting out from under your feet indicate you have found a sensitive slab.

    Loose snow avalanches are a real concern. These will be easy to trigger and will release naturally on steep slopes receiving direct sun. Importantly, any of these smaller slides can trigger the much larger and more dangerous Persistent Slab Avalanches described above.

Avalanche Discussion

It's been a wild week! Two multi-day Atmospheric River events raised the danger to HIGH for six of the last seven days. Weather stations recorded 2.5-3.5" of snow water equivalent (SWE) or ~2-4' of snow, more than doubling the snowpack depth across much of the zone.

These storms were too much too fast for the fragile weak layers near the base of the snowpack. Multiple human-triggered avalanches and dozens of natural avalanches were reported. Despite limited visibility, we observed multiple natural slab avalanches following Tuesday and Wednesday's storm (photos below).

Avalanche conditions remain dangerous. So far, most of the recent triggered and natural avalanches occurred on the more shaded N-half of the compass, where heavy slabs overlie a stack of weak facets and depth hoar.Before you head out today, have an honest discussion with your partners. Pick terrain you're comfortable with and, more importantly, terrain that you plan to avoid. Don't let powder sway you from this plan. Understand that even a low-angle ridge walk has consequences. Consider the very real possibility that a slide you trigger may affect an unsuspecting party below. 

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