Boletín de aludes

Central Sierra Nevada

Sierra Avalanche Center
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Peligro de aludes

Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
Desactualizado: este boletín caducó 10 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche danger will rise to CONSIDERABLE today at all elevations as hurricane force winds and heavy precipitation impact the region. Human triggered wind slab avalanches and wet loose avalanches will become likely today. As snow levels lower this afternoon and evening, wind slabs will become more widespread and larger and loose wet snow instabilities will become smaller and more isolated. Natural avalanches will become possible this afternoon and during the night as more snow accumulates. 

Problemas de aludes

  • Wind Slabs

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

    More snow and hurricane force winds will build new wind slabs on leeward aspects. The largest of these wind slabs will exist on wind-loaded N-NE-E aspects and cross-loaded SE and W-NW aspects above 8500 ft. where more precipitation falls as snow. As snow levels start to fall this afternoon and evening, wind slabs will form on lower elevation slopes and become larger and more widespread. Due to the strength of the winds at all elevations, wind slabs could exist in below treeline terrain as well as near and above treeline terrain. Human triggered wind slab avalanches will become likely on any slopes exposed to wind loading where significant snow accumulates today. Some natural wind slabs avalanches may become possible this afternoon and evening in areas where the most wind loading occurs. In areas where the precipitation falls as rain, wind slabs will be unlikely.

    Looks for signs of recent wind loading such as cornice features and wind pillows to help identify where problematic wind slabs are likely to exist.

  • Loose Wet

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

    Wet loose avalanches and instabilities like point releases, pinwheels, and roller balls will remain possible today on steep slopes below 8500 ft. that receive additional rain. If snow levels climb higher than 8500 ft. these wet snow instabilities will become more widespread; if the snow levels fall lower than 8500 ft. the wet snow issues could become less widespread. Since the snowpack has well-established drainage to deal with the additional rain, wet slab avalanches remain unlikely, but they are not impossible in some areas. 

    Most loose wet snow avalanches should remain small, but they could still knock a person off balance or cause a twisting fall. Be aware of terrain traps that could magnify the consequences of loose wet avalanches. 

Avalanche Discussion

Yesterday observations on Tamarack Peak and Elephant's Hump revealed wet rain-soaked snow up to ~9500 ft. Some loose wet instabilities like point releases, roller balls, and pinwheels occurred on steep slopes. In both areas, evidence of well-established snowpack drainage existed including rain runnels up to ~9000 ft, free water flowing out of the bottom of the snowpack, and rapid increases in nearby stream flows. Ski cuts and cornices dropped onto steep test slopes did not trigger signs of instability. Settlement cracks, hand pits, and probing all also pointed to consolidation and settlement in the snowpack.

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