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
1 · Faible
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Increasing winds will create wind drifted snow in near and above treeline areas today.  MODERATE avalanche danger will exist in near and above treeline areas due to wind slabs, with  LOW avalanche danger in below treeline terrain.

Problèmes avalancheux

  • Wind Slabs

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

    Human triggered wind slab avalanches will be possible today in near and above treeline areas.  SW winds have increased this morning and are forecasted to be in the strong to gale force range today.  Blowing snow should be limited to areas near and above 8000', above the recent rain where lighter snow that can be wind transported exists.  Wind slabs are expected to be larger along the Sierra Crest where 6 to 8'' or more of recent storm snow exists for wind transport. 

    Blowing snow, built out cornices, scoured ridges, and wind pillows will all be clues to where new wind slabs exist.  Use caution around these areas and manage terrain to avoid areas of concern.   

Avalanche Discussion

Observations from Mt. Judah (Donner Summit area) showed a mostly stable snowpack.  Light rain was falling on Donner Summit in the morning with a breakable surface crust below 7500'.  Wind slabs were non reactive on multiple test slopes below 7800'.  Blowing snow and larger new cornices were seen above 8000' along the summit ridge.  Snowpack tests targeting the Jan 4 weak layer showed this layer has gained strength and failure of this layer is unlikely moving forward. 

Similar conditions were seen at Blue Lakes (Carson Pass area).  Breakable crusts existed below 8000', with over 1' of snow in wind blown locations above 8000'.  Buried surface hoar was found beneath the newest crust.  Multiple snowpack tests and informal observations did not indicate that this layer was a concern.

Both locations reported multiple small D1 loose wet avalanches that occurred during the recent rain events. 

Régions couvertes