Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 10 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

MODERATE avalanche danger exists for all elevations today. Wet loose and wind slab avalanche problems remain an ongoing concern. Precipitation intensity will be dramatically less today than yesterday and the snowpack has had time to establish drainage for rain on snow. Human triggered avalanches remain possible today. Natural avalanches are unlikely, but not impossible today in isolated areas. Exercise caution for travel in or below backcountry avalanche terrain.  

Problèmes avalancheux

  • Loose Wet

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

    Rain soaked surface snow below 8,500' to 9,000' will remain prone to wet loose avalanche problems today. The vast majority of wet loose avalanche activity is expected to be human triggered and occur on any aspect where wet surface snow exists. This avalanche problem will exist on slopes steeper than 35 degrees.

    Consider how terrain features below such as cliffs or terrain traps could magnify the consequences of being pushed around by a wet loose avalanche.

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2

    Above 8,500' to 9,000' where significant amounts of new snow have accumulated, wind slab avalanche problems remain an ongoing concern. Unstable wind slabs are most likely to exist near treeline and above treeline on NW-N-NE-E-SE-S aspects on slopes 35 degrees and steeper. Wind slabs could exist in isolated areas below treeline or on SW-W aspects as well due to the strength of the recent winds. Avalanche size could be fairly large at the upper elevations.

    Looks for signs of recent wind loading such as cornice features and wind pillows to help identify where problematic wind slabs are likely to exist.

Avalanche Discussion

Observations made yesterday on Andesite Ridge (Donner Summit area) revealed that a widespread cycle of wet slab avalanches had occurred from rain on recent new snow. Some avalanches appeared older than others indicating that the cycle was not limited to a short specific time window. Signs of numerous avalanches size D1 and D2 were seen on N-NE-E-SE aspects in the Donner Summit area. Significant amounts of standing and running water were noted at pass level (7,227'). Poor visibility greatly limited the ability to see signs of avalanche activity in the higher surrounding terrain.

Régions couvertes