Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 9 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

HIGH avalanche danger exists in near and above treeline terrain with CONSIDERABLE danger in below treeline areas due to wind slabs and storm slabs. Natural and human triggered avalanches are very likely today. Dangerous avalanche conditions exist in the backcountry today. Travel in avalanche terrain is not recommended.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2

    New snow and gale force southwest winds during the storm have created problematic wind slabs on wind-loaded slopes. As more snow and wind impact the forecast area today, these wind slabs will become larger and more widespread. Human triggered and natural wind slab avalanches will be likely today. Some of these wind slabs will be deep, large, and would have very serious consequences. The largest and most fragile wind slabs will exist on the wind loaded N-NE-E aspects and on cross-loaded NW and SE aspects in near and above treeline terrain, but wind slabs could also exist in some below treeline areas due to the strength of the winds. 

    Identify where wind slabs might exist by using clues like blowing snow, wind drifts, cornices above slopes, wind-created ripples, and other wind created features. Use this information to avoid the wind slabs.

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1

    Changing snow levels and accumulation rates will create weak layers and slab layers within the storm snow. Human triggered storm slab avalanches will be likely today and some natural storm slab avalanches may be possible. Storm slabs could exist on steep slopes in non-wind-affected terrain and could involve enough snow to bury or injure a person. The areas that receive the most new snow and highest snowfall rates will represent the best places to find storm slabs. Storm slabs and/or loose wet snow instabilities will also be likely in any areas where rain falls on new snow.

    Recent avalanche activity, shooting cracks, snowpits, and probing can all help identify where storm slabs may exist. Use this information to avoid steep slopes where storm slabs may exist. 

Avalanche Discussion

Observations on Elephant's Hump at Carson Pass yesterday found wet snow with minor amounts of new snow on the surface. Strong winds and blowing snow had already formed small wind slabs (up to 6 inches deep) on some wind-loaded slopes. Ski cuts on wind-loaded test slopes did not trigger shooting cracks or slab failures but did result in some loose wet snow instabilities. Overall the snowpack appeared to be ready to handle the new snow load.

Due to uncertainty concerning snowfall amounts the avalanche hazards could vary greatly from place to place. In areas that receive the high end of forecasted snow amounts, more avalanche danger and larger avalanche problems will exist. In areas where snow totals only reach the low end of the forecasted accumulation, the avalanche problems could be smaller and less widespread.

Regioni coperte