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
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Non aggiornato — questo bollettino è scaduto 8 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger exists at all elevations today. Human triggered avalanches remain possible. Some unstable storm slabs and wind slabs may still linger in some areas. If any doubts exist about the stability of a slope, avoid it and move on to something lower angle with less uncertainty.

Problemi valanghivi

  • Loose Dry

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

    As the skier-triggered avalanche from yesterday highlights, some lingering unstable storm slabs may still exist in near and below treeline terrain especially if they rest on top of a thin weak layer of surface hoar. A high degree of uncertainty exists as to where these storm slabs may linger and whether or not they remain unstable. Triggering one of these storm slabs may be easier in areas with numerous trigger points (like convex rollovers, shallowly buried rocks, cliffy areas, etc) or in more complex terrain. They could potentially involve enough snow to bury or injure a person especially in areas around terrain traps. 

    Recent avalanches, shooting cracks or collapses, or unstable snowpit tests can all help identify where unstable storm slabs may still exist. Actively look for signs of instability and avoid areas with potential problems. In some cases, this problem could lurk in an area where most data seems to indicate stability. If in doubt, assume a slope could remain unstable and avoid it. The high degree uncertainty associated with this problem makes more conservative decision making a good strategy. Low angle slopes are holding great snow and provide less potential for hitting barely covered obstacles.

  • Wind Slabs

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

    Wind slab avalanches should have become more difficult to trigger in most places. However, some human-triggered wind slab avalanches may remain possible today in near and above treeline areas on wind-loaded N-NE-E aspects and cross-loaded NW and SE aspects. Avalanches resulting from these wind slabs could involve enough snow to bury a person (size D2). Like the storm slabs mentioned above, triggering these lingering wind slabs could be easier in more complex terrain with numerous trigger points.

    Use clues like cornices above slopes, wind pillows/drifts, ripples on the snow surface, and other signs of wind-loading to identify and then avoid places where wind slabs may exist. Plenty of great snow and recreation opportunities exist on lower angle more sheltered slopes.

Avalanche Discussion

* A skier-triggered avalanche occurred on a 35 degree, NE facing slope at 9400 ft. on Red Lake Peak yesterday. One skier was caught, but not buried. No injuries resulted. For more information click here or on the observation below. The weak layer remains unknown, but the party who triggered it speculated that it may have been a lingering patch of buried surface hoar. 

* Surface hoar (weak feathery snow crystals) had formed on the current snow surface on all aspects and elevations on Elephant's Hump.

* Good snow coverage exists in many places, but there are still many obstacles/trigger points on or near the snow surface in some areas.  

Regioni coperte