Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 10 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Following a period of HIGH avalanche danger last night, CONSIDERABLE avalanche danger will exist today near and above treeline on all aspects on slopes 35 degrees and steeper due to newly formed wind slabs. In wind protected areas below treeline, MODERATE avalanche danger exists on slopes 35 degrees and steeper due to storm slabs. Large human triggered avalanches are likely today. Another period of HIGH avalanche danger is expected tonight into early tomorrow morning with natural avalanches likely.  

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    3

    New snow and winds last night created wind slabs several feet deep in wind loaded areas near and above treeline. The vast majority of unstable wind slabs will exist on NW-N-NE-E-SE aspects. Wind slabs may be found on S-SW-W aspects in isolated areas. Avalanche size could be large and destructive depending on location and depth of wind loading. These new wind slabs have been deposited on top of unstable wind slabs formed Friday night.

    Look for areas of recent wind loading and avoid steep wind loaded slopes. Use clues such as recent avalanche activity, blowing snow, cornice formations, and wind pillows to identify wind loaded areas to be avoided. Human triggered shooting cracks are a sign of instability in the immediate area and cause to seek out terrain less than 30 degrees in slope angle.

  • Loose Dry

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

    In wind protected areas below treeline, storm slab instability is possible today on all aspects. The snow that has fallen over the past 40 hours has been variable in both density and moisture content, setting up significant layering within the recent storm snow. Human triggered storm slab avalanches are an ongoing concern today in steep areas below treeline. Large openings are not required. Tree density must be too tight to ski or snowmobile through in order to anchor the snowpack in place. Trees you can ski or ride through only provide protection from the wind and wind related avalanche problems, not from storm slabs.

    Clues such as recent avalanche activity below treeline, shooting cracks, and/or snowpack collapse indicate that conditions are locally unstable. Large column snowpit tests can be helpful in finding signs of instability when the more obvious clues are not observed.

Avalanche Discussion

Observations made yesterday on Jake's Peak (West Shore Tahoe area) revealed widespread small natural and human triggered loose wet avalanches as well as signs of unstable wind slabs. Signs of unstable wet snow existed on all aspects all the way up to the summit around 9,200'. New snow amounts in the area from Friday night ranged from 2 to 3 inches around 7,500' to 8 inches above 8,200'. Skier triggered cracking of wind slabs was noted in wind loaded areas along the summit ridgeline. At mid day yesterday wind slab depth was around 1 foot. See specific observations below for more info, photos, and video.

Regioni coperte