Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 11 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger exists on slopes 35 degrees and steeper at all elevations and on all aspects today due to newly formed wind slabs, storm slabs, and some persistent slabs. The NW-N-NE-E-SE aspects represent the best places to trigger an avalanche since more than one avalanche problem may exist on those aspects. Evaluate snow and terrain carefully to make backcountry travel decisions. Human triggered avalanches are possible today.

Problemi valanghivi

  • Wind Slabs

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

    Human triggered wind slab avalanches will be possible today. Expect to find wind slabs on the near and above treeline wind-loaded and cross-loaded NW-N-NE-E-SE aspects today. Since the winds shifted between the W and SW, some cross-loading may have occurred on some S facing slopes as well. These winds slabs have formed on top of frozen crusts and may not have bonded to the old snow surfaces very well. Most of these slabs should measure 1-3 ft. in depth with some smaller or larger ones scattered across the region depending on the amount of new snow that fell in a particular area.

  • Loose Dry

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

    Some human triggered storm slab avalanches may also be possible today on any slopes that had previous snow cover. Like the wind slabs mentioned above, these storm slabs will vary in depth depending on how much snow a specific location received and could range from a few inches to a foot in depth. They have formed above frozen crusts in most areas and have not had time to form good bonds with the old snow surfaces. In addition to the possiblity of storm slabs, some loose snow sluffing may also occur on steep slopes today.

  • Deep Persistent Slabs

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

    Prior to this storm, near surface facets existed on isolated near and below treeline NW-N-NE wind sheltered and shaded slopes above 8000 ft. This soft weak layer of snow rests above a frozen rain crust that could serve as an efficient bed surface for snow to slide on. Prior to the storm, the only avalanche ingredient missing was a slab on top of the weak layer/bed surface combination. The new snow deposited by this storm has the potential to be that slab. In areas where the new snow has accumulated above the persistent weak layer of near surface facets (soft weak sugary snow), human triggered persistent slab avalanches may be possible today. These kind of avalanches tend to release farther away from the person who triggers them often times causing the slope above them to release.

Avalanche Discussion

Yesterday on Incline Lake Peak, the snow surface consisted of a mix of skier scrapped crusts, thin melt-freeze crusts, and small patches of soft weak near surface facets. On the northerly aspects where the patches of near surface facets existed, they rested above a frozen crust in the upper snowpack. During the morning a small snow shower dropped .5 to .75 in. of new snow, and this new snow had trouble bonding to the old snow surfaces. Ski cuts on steep test slopes caused it to sluff off of the crusts. 

Regioni coperte