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

Points saillants

MODERATE avalanche danger will exist at all elevations today as a loose wet avalanche problem develops in response to daytime warming. Monitor snow surface conditions and avoid travel in or below avalanche terrain in areas where the snow surface is marginally supportable to unsupportable, where human triggered roller balls are occurring, or where loose wet avalanches are actively occurring.

Problèmes avalancheux

  • Loose Wet

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

    A decent snow surface refreeze is expected to have occurred last night from radiational cooling under clear skies. This is despite at or above freezing air temperatures last night in most locations. Rapid warming conditions and well above freezing air temperatures today will lead to another round of loose wet avalanche problems that develop as the day progresses. Loose wet avalanches will be possible today on all aspects at all elevations. Avalanche size up to D2 is possible (large enough to bury or injure a person).

    Mid and upper elevation NW-N-NE aspects may see human triggered roller balls as an indication of potential unstable conditions as the recent storm snow continues to transition to corn. Where melt-freeze conditions are more established on E-SE-S-SW-W aspects, focus on monitoring snow surface supportability. Once the snow surface is in melt phase and conditions become marginally supportable to unsupportable, avoid travel in or below avalanche terrain.

Avalanche Discussion

* Observations were made yesterday on Maggie's Peak South (Desolation Wilderness Area). Warming conditions and snow surface melt were observed in this area on all aspects. Recent storm snow on E-SE-S-SW-W aspects in the 7,500' to 8,500' elevation range was mostly assimilated with the older melt-freeze snow below. Loose wet avalanche problems had developed by the early afternoon hours, especially on the more northerly aspects above 7,500' where the recent storm snow was entering into melt phase for the first time.

* The high sun angle this time of year is allowing for significant amounts of incoming solar radiation on NW-N-NE aspect terrain that is otherwise well shaded from November through February.

* Snow cover below 7,200' to 7,500' is becoming very thin to nonexistent in many portions of the forecast area. There are a few areas of exception.

Régions couvertes