Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Alpin
1 · Faible
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 13 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche danger remains MODERATE near treeline and below treeline on NW-N-NE aspects on slopes 32 degrees and steeper due to ongoing persistent slab instability.

Current conditions remain conducive to human triggered avalanches.

Problèmes avalancheux

  • Deep Persistent Slabs

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

    Near treeline and below treeline slopes on NW-N-NE aspects continue to present a risk for human triggered avalanches. Slopes that resisted scouring by the Nov 21-23 ENE gale force wind event hold significant amounts of faceted snow below the upper layers of 10 day old storm snow. This is the Dec 7 persistent weak layer with its overlying slab. This weak layer can collapsed under the weight of a person and has shown the ability to propagate from tens of feet to hundreds of feet. Under the current conditions, it is possible to trigger an avalanche either high on the slope, low on the slope, or remotely.

Avalanche Discussion

Various locations around the forecast area are starting to show variability in the amount of instability associated with the faceted Dec 7 persistent weak layer. In some areas, obvious signs of instability continue to present with impressive amounts of whumphing and cracking occurring on a regular basis. In other areas, the triggering of snowpack collapse, shooting cracks, and other obvious signs of instability are becoming less frequent. In these areas evidence of instability is still very apparent in snowpit tests. Take steps to constantly mitigate hazard. Don't get caught by surprise.

See below for more detailed information on recent observations from Becker Ridge (Echo Summit area), Upper Ophir Creek (Mount Rose area), and from the Deep Creek drainage.

Régions couvertes