Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Alpin
1 · Faible
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 13 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche danger is LOW for snow covered areas at all elevations on NW-N-NE-E aspects. For all other areas, avalanche danger is generally non-existant due to a lack of snow cover.

Problèmes avalancheux

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1

    The remote possibility of finding that third scenario of the unlikely but not impossible to trigger persistent slab is just enough to warrant continued caution and diligent best practice travel techniques in the backcountry. The faceted Dec 7 persistent weak layer remained reactive for 3+ weeks following the snowfall event that buried and loaded it. It has just recently gone quiet in the areas sampled by field observations. Near treeline and below treeline slopes on NW-N-NE aspects that hold continuous snow cover still deserve respect. No one will care how "unlikely" triggering is on a regional scale if caught in an avalanche on the one slope for miles around that still holds instability. Persistent weak layers are stubborn that way.

Avalanche Discussion

Observations made yesterday in the Mount Rose Backcountry fell in line with other observations from around the forecast area over the past several days. Where areas of continuous snow cover exist near treeline and below treeline on NW-N-NE aspects, generally one of two snowpack scenarios is found. Either the faceted Dec 7 layer has gained enough strength that failure has become unlikely under the current level of load or the slab sitting on top of the Dec 7 facet layer has lost so much cohesion through the near surface faceting process that it will no longer sustain propagation upon collapse. Either way human triggered avalanches have become unlikely at this time. Finding a third scenario of a lingering pocket of isolated persistent slab instability on an isolated terrain feature somewhere within the forecast area is unlikely but not impossible.

Régions couvertes