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 due to the possibility of wind slabs and loose wet avalanches.  Ongoing SW winds could continue to build wind slabs on NW-N-NE-E-SE aspects near and above treeline.  Loose wet avalanches will become possible throughout the day as temperatures warm and snow levels increase on all aspects below treeline.  Evaluate snow and terrain carefully, identify areas of concern.

Problèmes avalancheux

  • Wind Slabs

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

    Strong SW winds above 8000' through today will continue wind slab development on NW-N-NE-E-SE aspects near and above treeline on slopes steeper than 35 degrees.  There was plenty of snow yesterday available for transport on windward slopes for ongoing wind slabs to form.  In some areas, these winds slabs could form on top of existing wind slabs from the last couple days that have not fully bonded and gained strength. 

    Identify and avoid steep wind loaded slopes.  Look for areas of blowing snow, cornice formation, wind scouring, and wind pillows to help determine where wind slabs exist.

  • Loose Wet

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

    Loose wet avalanches will become possible on all aspects below treeline today as temperatures warm and snow levels rise.  Snow level is forecasted to rise to 7500' by 11am with light precipitation.  Most loose wet instabilities should be in the form of roller balls and pinwheels.  If we receive more rain than expected or rain levels go to higher elevations, loose wet avalanches could become more widespread and larger in size.

    Avoid slopes that are steeper than 35 degrees or have terrain above that is 35 degrees as warming occurs in the late morning.  Active roller balls and pinwheels are indications that the snow surface is loosing strength and it's time to get off steeper terrain.

Avalanche Discussion

We made or received observations yesterday from Castle Peak (Donner Summit area), Jakes Peak (West Shore area), NW of Estelle Bowl (Five Lakes area), Hell Hole (Luther Pass area), and Andesite Peak (Donner Summit area).  Most areas experienced rapid warming with increased solar radiation in the mid morning hours before cloud cover and SW winds increased by mid day.  Blowing snow was visible with active wind loading on Freel Peak, in the higher peaks of Desolation Wilderness, and in the Five Lakes area by mid day.  Light snow began to fall in most areas by 1pm.  Small wet point releases were observed on Jakes Peak on SE-S aspects during the morning hours with full sun.  Little other instabilities were observed as the recent storm snow continues to gain strength. 

Régions couvertes