Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
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

Firm wind slabs remain reactive to human trigger primarily above treeline. Large patches of wind-affected snow should be treated with caution. Manoever around these aging wind drifts on slopes steeper than 35 degrees.

Problemas de aludes

  • Wind Slabs

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

    Wind slabs will be around 3 days old by Friday. They remain reactive above treeline, but they might need a steep, unsupported slope to trigger them. Steer around this terrain where you find wind-textured snow surfaces such as the snow surface pictured. Stiff over weak snow layering, hollow-sounding snow, or cracking snow surfaces all indicate slabs may be reactive in your terrain.  Near treeline, wind slabs we expect that wind slabs may be losing reactivity.

    (3/10/2022)

    Wind slab instability in snowpack tests.

    Photo: Andrew Kiefer

Avalanche Discussion

NWAC forecaster Andrew Kiefer traveled above NWAC forecast terrain on the south side of Mt. Hood. He found a variety of hazards at these elevations. Natural avalanche activity was generally more than 24 hours old and included a large avalanche released from a rock slab and multiple shallow slab avalanches visible on the west face of Mt. Hood. A large crevasse was opening on the White River Glacier. He also identified reactive interfaces within wind slabs up to 1 ft thick. These reactive wind slabs likely extend down into NWAC forecast terrain.

Warming temperatures and sunshine on Thursday got some small rollerball activity going, but no fresh wet loose avalanches were reported.

A storm system 3/8 - 3/9 brought 4-8" of fresh snow with higher snow totals on the west and north sides of the mountain. Strong WNW winds redeposited the new snow early in the storm.  This snow sits on a variety of surfaces left by the 2/26-3/2 atmospheric river event which deposited tree debris on the new/old snow interface and also left a few south and west-facing slopes melted out to the ground. Between 5500-6500ft, wind slabs or loose snow may sit on 3-5in of cold recycled powder. Slabs sitting on this interface may propagate farther than you expect, making them more difficult to manage. Sugary snow might continue the dry loose avalanche activity reported by Mt. Hood Meadows Pro patrol. These avalanches should only be problematic in very steep or extreme terrain. Above 6500ft, the storm snow sits on previously wind-affected and at the highest elevations while rime ice intermixes with wind slabs at the very highest elevations.

Several very large natural avalanches released high on the mountain during the atmospheric river. In a few cases, these avalanches ran through the rain/snow line around 8000ft and entrained significant wet snow creating very large, river-like debris piles. Check out a few of the largest documented avalanches from the 2/26-3/2 atmospheric river in our avalanche occurrence database: Clark Canyon, Eliot Glacier Headwall, White River Canyon.

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