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 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Shifting winds and new snow mean that fresh slabs of wind drifted snow could exist on almost any exposed slopes today. In more sheltered areas soft slabs of new snow or loose cohesionless new snow may exist. Expect wind slab, storm slab, and loose dry avalanche problems today. CONSIDERABLE avalanche danger exists near and above treeline with MODERATE danger below treeline. 

Problemi valanghivi

  • Wind Slabs

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

    Slabs of wind drifted snow could exist on almost any aspect today as a result of both SW and NE winds. At first, fresh wind slabs will be most prominent on NW-N-NE-E-SW aspects. As the wind shifts to the NE and increases, some wind slabs will migrate to the SE-S-SW-W-NW aspects. This wind shift started at the northern end of the forecast area last night and should move south through the forecast area today. Today's wind slabs could measure a few feet in depth and could involve enough snow to bury or injure a person. They may not bond well to the old snow surfaces and the weight of a person recreating on a wind loaded slope could trigger wind slab avalanches today. Some natural wind slab avalanches may also be possible in areas with heavy wind loading today.

    Use clues like blowing snow, drifted snow, cornices above a slope, and other wind created textures to identify where wind slabs may exist. This information can help create safety margins that avoid potential wind slabs and lead you to less wind-affected snow.

  • Loose Dry

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

    Changes in snowfall rates and other conditions during this storm could create weaknesses within the storm snow. In some areas, the new storm snow may not bond well to the old snow surfaces. As a result of either of these weaknesses, soft slabs of storm snow could break loose today on some steep slopes where the new snow has enough cohesion to break as a storm slab. These storm slabs would only involve the new snow but they could still entrain enough snow to be problematic. 

    Signs of a storm slab problem include recent avalanches, shooting cracks, or feeling softer layers of snow under more dense layers of snow. Watch out for steep slopes where these clues exist. Lower angle sheltered slopes will provide excellent recreation conditions today. 

  • Wet Slabs

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

    In some cases, the sliding snow may lack cohesion and move as more of a loose dry snow sluff. While these may not entrain as much snow as the other problems mentioned above they could still push a person into a terrain trap or knock a person over. 

Avalanche Discussion

* Yesterday observations continued to show a wide variety of snow surfaces. Sun-exposed E-SE-S-SW-W aspects held melt-freeze conditions and NW-N-NE aspects held a mix of firm icy scoured surfaces, breakable crusts, and some softer surface snow (facets).

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