Boletín de aludes

East Slopes South

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 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You can trigger an avalanche on wind-loaded slopes at upper elevations, particularly in areas further west in the zone that received more snow. Carefully assess how new and wind-drifted snow is bonded to variable old snow surfaces before committing to larger features. Seek out lower-angle terrain sheltered from the wind to reduce your risk

Problemas de aludes

  • Wind Slabs

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

    Avalanches in wind drifted snow will become larger and easier to trigger as you gain elevation. These avalanches could fail on the icy (and potentially weak) old snow surface buried January 30th, or within new and wind drifted snow. Avalanches will be easiest to trigger on east through north aspects in terrain 35 degrees and steeper. Steer around large open slopes below cornices, cliff bands, and ridgelines with evidence of fresh wind loading. Look and feel for changes in snow surface texture and hardness. You may find windward slopes scoured to the old icy surface, and leeward slopes drifted in with chalky snow. Use these visual clues along with blowing snow as the easiest tools to identify slopes with fresh wind slabs. If you experience cracking or see recent avalanches, choose lower angled terrain sheltered from the wind.

    (2/1/2022)

    Example of bllowing snow and wind loading near treeline in the nearby Snoqualmie Pass Zone.

    Photo: Dallas Glass

Avalanche Discussion

Incremental snowfall over the past 4 days brought storm totals up to 6-10in throughout the East South Zone. The new snow provided a much-needed refresh after a prolonged period of dry, sunny weather. The improved riding conditions come with an uptick in avalanche danger at upper elevations, especially in areas closer to the Cascade Crest that received more snow. Carefully evaluate new and windblown snow before committing to steeper terrain. You may find fresh slabs generally 1ft thick or less, but triggering a deeper, larger wind slab in the alpine is not out of the question.

The new/old snow interface (Late January Crust) is a pronounced marker in the snowpack throughout the region and something to track closely moving forward. Although the recent storm started warm and wet, new snow may take time to bond to slick and icy old snow surfaces. In some isolated areas, weak snow may exist above or below the old crust and be capable of producing surprising avalanches. The old snow surface will be easy to find, so gather information as you travel. Build in a wide margin for error and move to lower angle terrain if you experience shooting cracks, collapses, or see recent avalanches break widely across terrain features. The Late Januaury Crust may even be exposed or shallowly buried in some areas, especially in windward terrain (S and W aspects), and below treeline where less snow accumulated. In these slippery areas, anticipate lingering travel hazards.

Prior to the storm this week, conditions in January were unseasonably warm and the snowpack endured a beating. There was a significant loss in overall snow height, and many ridgelines, south aspects, and low elevation slopes melted out to bare ground. Several creeks also reopened during the warm weather and many snow bridges fractured or collapsed. Shallowly buried obstacles are additional hazards to deal with hidden beneath the new snow. 

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