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 12 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche danger is LOW for all elevations and aspects. Low likelihood high consequence large size persistent slab avalanches remain a lingering concern in isolated areas above 9,000' on NW-N-NE aspects both above and below treeline.

Problèmes avalancheux

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    3

    Persistent slabs remain a lingering concern in isolated areas above 9,000' on NW-N-NE aspects both above and below treeline. Recent snowpit data has shown that the Dec 2 facet layer is gaining strength in most, but not all areas. At this time, triggering a persistent slab avalanche is a low likelihood, high consequence event. Given the location of the problematic weak layer near the base of the snowpack, nearly all of the existing snowpack (2 to 4+ ft deep) will be involved. The potential avalanche size and the density of the overlying slab make survival without significant traumatic injury an unrealistic expectation. The most likely trigger points exist at relative shallow areas of the snowpack. These are commonly found near exposed rocks, isolated trees, and along cliff bands, making travel in northerly aspect complex terrain above 9,000' a poor choice at this time.

Avalanche Discussion

Observations made yesterday on Andesite Ridge (Donner Summit area) and on Powderhouse Peak (Luther Pass area) revealed stable snowpack conditions. Evidence of rain on snow existed up to 8,300' on Powderhouse Peak and potentially higher in the Donner Summit area. Snowpit tests targeting the Dec 2 facet layer on Powderhouse Peak at 9,260' revealed increasing strength of this layer. Other recent observations targeting this same layer have shown mixed results on Tamarack Peak (Mount Rose area) and unstable results on Red Lake Peak (Carson Pass area).

Régions couvertes