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

Points saillants

Avalanche danger for today is Low on all aspects and elevations.  In the afternoon hours, isolated human triggered loose wet avalanches could become possible on E-SE-S-SW aspects on slopes steeper than 37 degrees.  Normal caution is advised.

Problèmes avalancheux

  • Loose Wet

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

    Overnight temperatures were in the mid 30's to mid 40's above 8000'.  Winds have shifted from the NE-E direction to the SW and are forecasted to be in the moderate range for today.  Clear skies overnight have allowed for radiational cooling to provide a decent snow surface refreeze where air temperatures were above freezing.  Snow surface melt is expected to occur faster than yesterday due to warmer overnight temperatures and the shift to the warmer SW wind direction.  

    Snow surface conditions are expected to be supportive through most of the morning hours.  By midday or early afternoon, human triggered loose wet avalanches could become possible in isolated areas on E-SE-S-SW aspects at all elevations.  These loose wet instabilities are expected to be human triggered and in the form of roller balls or pinwheels.

    Planned timing of travel in avalanche terrain is critical to finding supportable snow conditions.  If boot penetration becomes 1' deep or greater, it is time to take active measures to avoid avalanches.   Change to a more northerly or westerly aspect and/or move to slopes less than 35 degrees in slope angle without steeper terrain above. 

Avalanche Discussion

Recent observations from Castle Peak (Donner Summit area) and Silver Peak (Pole Creek area) showed a good overnight refreeze with supportable snow conditions throughout most of the day.  On SE-S aspects, 2'' of wet snow existed on top of a pencil hard 4'' melt freeze crust during the mid day hours providing good corn snow conditions.  On Silver Peak in rocky areas with low snow coverage, < 1' deep, snow supportability was borderline by midday. 

Observations from Silver Peak on north aspects did not show any problematic weak layers in the upper snowpack.  Several rain crusts were noted without any problematic associated near crust faceting.

Régions couvertes