Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

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

Points saillants

An increase in avalanche danger my occur tonight into tomorrow. For today avalanche danger remains LOW at all elevations on snow covered NW-N-NE-E aspects. Avalanche danger is generally nonexistent on SE-S-SW-W aspects due to the lack of snow cover. The possibility of rain on snow tonight has the potential to increase avalanche danger. Depending on how much rain reaches the ground, natural wet loose snow avalanches could occur late tonight and early tomorrow morning.

Problèmes avalancheux

  • Cornices

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

    During the daylight hours today, avalanche activity on a region scale remains unlikely. Due to the variability associated with faceted persistent weak layers such as those buried in the current snowpack, finding a localized area of unstable snow is not impossible. If this were to occur, it would present as a small persistent slab on an isolated terrain feature located near treeline or below treeline on a NW-N-NE aspect.

    For this reason, it remains prudent to evaluate the snowpack before committing to a slope. Stack the odds on survival through the use of backcountry travel practices such as traveling one at a time through avalanche terrain and by spotting partners from known safe zones outside of the avalanche path. Numerous rocks, trees, stumps, logs, and other obstacles remain exposed and present an additional hazard for injury and equipment damage.

  • Loose Wet

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

    After precipitation arrives tonight, the possibility of naturally occurring wet loose snow avalanches will increase. Locations where rain falls on well developed near surface facets are the expected problem areas. NW-N-NE aspects between 7,000' and 8,000' is where this avalanche problem is most likely to occur. Some isolated E aspects may become involved as well. Steeper slope angles upwards of 37 degrees may be necessary for avalanche activity to initiate.

Avalanche Discussion

Observations made yesterday on Lincoln Ridge (Yuba Pass area) showed a continuation of the area wide snowpack trend of significant near surface faceting and buried facet layers within the snowpack. The snowpack that exists near treeline and below treeline on NW-N-NE aspects has shown indications that it is weak but stable at this time. Buried weak layers have generally shown the ability to support the current load of the shallow overlying snowpack, plus the weight of a person traveling on the snow surface.

With the potential for precipitation on the horizon, it is important to understand that despite the persistent drought pattern, the existing snowpack on NW-N-NE aspects is in poor condition to handle new loading from either rain or snow. Once significant precipitation is added, the existing snowpack is likely to rapidly change from stable to unstable.

Régions couvertes