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

Points saillants

MODERATE avalanche danger exists this morning due to the potential for loose wet and wet slab avalanche problems. In areas that received little to no snow surface refreeze last night these problems are possible beginning early this morning. In areas where a refreeze did occur these avalanche problems will develop as daytime warming occurs, accelerating once cloud cover clears from the area today. Avoid travel in avalanche terrain once wet surface snow begins to loose supportability.

Problèmes avalancheux

  • Loose Wet

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

    Cloud cover and above freezing air temperatures in many locations last night are expected to have allowed for a poor to at best decent overnight snow surface refreeze. The amount of refreeze could vary significantly from one location to another around the forecast area this morning. Cloud cover and wind this morning may slow the rate of surface wet snow formation. Sunny skies and well above freezing air temperatures by this afternoon are expected to allow for loose wet avalanche problems to form on all aspects today. In areas with little to no refreeze last night this avalanche problem will exist this morning. In any areas where a decent refreeze occurred, this avalanche problem may hold off until the late morning or early afternoon hours.

    Avoid travel in avalanche terrain once wet surface snow begins to loose supportability.

  • Persistent Slabs

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

    Wet slab avalanche problems are unlikely, but not impossible today. The areas most conducive to wet slab avalanches are in near treeline or above treeline terrain on SE-E aspects where the best mix of past wind loading and current snowpack warming overlap. In these areas recent storm snow exists below the surface melt freeze snow and is receiving melt water percolation during daytime melt.

    Avoid travel in avalanche terrain once wet surface snow begins to loose supportability.

Avalanche Discussion

Observations made yesterday morning on Incline Lake Peak (Mount Rose area) revealed a good overnight refreeze on E-SE-S-SW aspects but just a thin breakable crust on N-NE aspects. Signs of loose wet instability existed at 9,500' on a NE aspect along the summit ridge at 9:50 am.

A report was received of a skier triggered wet slab avalanche occurring around noon in the Rose Knob/Third Creek Drainage (Mount Rose area). The avalanche occurred on a SE aspect around 8,500'. The avalanche failed about 1 foot deep and 60 feet wide. The avalanche was triggered by the fourth skier on the slope. The snowpack was reported by the party to have failed in recent storm snow below the surface layer of melt-freeze snow. Two snowpack collapses were noted by the party. One when the avalanche initiated and a seconded while the debris were moving down slope. The party reported that the snow surface had begun to loose supportability in the area prior to the avalanche occurrence.

Régions couvertes