Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

CONSIDERABLE avalanche danger exists above treeline and near treeline where wind drifted snow has formed into wind slabs. MODERATE avalanche danger exists below treeline due to the possibility of storm slabs and loose dry avalanches.

Problèmes avalancheux

  • Wind Slabs

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

    Recently wind drifted snow forming into wind slabs in lee areas is the main avalanche concern for today. Expect to encounter newly formed wind slabs in near treeline and above treeline terrain on NW-N-NE-E-SE aspects. Avalanche size up to D2 is expected. Freshly enhanced cornices are weak and could collapse easily under the weight of a person today.

    Make a plan to avoid wind slabs today. There are lots of other slopes to utilize. Identify the most likely location of wind slabs by using clues of recently wind drifted snow including cornices, wind pillows, and scouring vs deposition patterns along ridgelines.

  • Loose Dry

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

    Low end snowfall accumulations and a warm to cold storm have made conditions borderline for new storm slabs to have formed over the last 24 hours. If storm slab instability does not exist, expect loose dry avalanche problems (sluff) instead. If storm slabs did form, they could be encountered in wind protected areas below treeline on any aspect. The expected avalanche size is D1.

    Areas of snow surface cracking or recent avalanches in wind protected areas below treeline are signs of storm slab instability. Using lower angle slopes and avoiding steeper slopes above is a way to manage either a storm slab or loose dry avalanche problem.

Avalanche Discussion

Observations made yesterday in the Mount Rose and Carson Pass areas revealed blowing snow and fragile new cornices. Wind slabs were forming in lee areas where wind drifted snow was depositing. Snowpack stability was on a decreasing trend during the afternoon and evening hours.

Recent observations from around the forecast area indicate strong layer bonding in the lower and middle portions of the snowpack. Current avalanche problems are focused on the upper portion of the snowpack.

Régions couvertes