Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

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

In sintesi

Blowing snow and rapid snow loading during today's storm will create dangerous avalanche conditions. Watch out for slopes near ridges or in gullies where unstable slabs of wind-blown snow will exist and open slopes in sheltered areas where unstable storm snow may exist. Careful travel plans that focus on terrain not steep enough to avalanche can help avoid today's avalanche problems. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    New snow and strong SW winds will load snow onto the leeward side of ridges, in gullies, and on open slopes exposed to the wind today. This loading will create wind slabs that grow quickly as more snow accumulates throughout the day. These wind slabs may form faster than they can bond to the snow below them. Human-triggered wind slab avalanches large enough to bury or injure a person will become likely today. Some natural wind slab avalanches may also be possible in some areas. The largest wind slabs will exist in near and above treeline terrain on NW-N-NE-E-SE aspects. In areas where less new snow accumulates, smaller wind slabs will exist. 

    Watch out for signs of wind loading like blowing snow, cornices above a slope, snowdrifts, and wind-created surface textures. Conditions will change quickly today. Avoiding areas where fragile wind slabs might exist represents a good plan. Traveling on lower-angle slopes in wind-sheltered areas can help avoid potential wind slab issues and may provide softer, more consistent snow conditions.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Intense snowfall rates could create soft slabs of cohesive snow on top of weaknesses in the storm snow, and storm slab avalanches may become possible today. Storm slab instabilities could exist on steep slopes near and below treeline where new snow accumulates. Some storm slab avalanches could grow large enough to cause problems for backcountry travelers especially if people trigger them near a terrain trap like a creek, gully, or cliff that would magnify the consequences of an avalanche. As with the wind slabs mentioned above, smaller storm slabs will exist in areas where less snow accumulates.

    Look for cracking in the snow or signs of cohesion within the new storm snow to help identify where unstable storm slabs may exist. Keep evaluating conditions as you travel and be willing to move to lower angle terrain whenever you encounter signs of instability. 

Avalanche Discussion

  • Observations yesterday revealed that snow on cool shady slopes remained soft and cold, and warmer wetter snow formed on sunny slopes, especially at the mid and lower elevations. 
  • Many NW-N-NE-E aspects have good snow coverage, while large areas of bare ground or very limited snow cover existed on most SE-S-SW-W aspects prior to this week. Those previously bare slopes now have a few inches of snow on them.
  • Barely covered obstacles and hazards including exposed rocks, dirt, bushes, down trees, branches, open water, firm crusts, and running creeks exist on many slopes.

Regioni coperte