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

Points saillants

MODERATE avalanche danger continues for all aspects below 9,500' on slopes 35 degrees and steeper due to ongoing loose wet avalanche problems. Little to no snow surface refreeze is expected to have occurred last night. The minimal amount of new snow that deposits over the highest elevations today is not expected to create new avalanche problems. Evaluate snow and terrain carefully. Identify and avoid the areas where wet snow depth is sufficient for loose wet avalanches to occur.

Problèmes avalancheux

  • Loose Wet

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

    Rain on snow below 9,000' will continue to melt and weaken the snowpack today. Areas above 9,500' may slowly refreeze today, or at least stop producing free water. Free water drainage is fairly well established on E-SE-S-SW-W aspects at all elevations. Free water drainage is not yet established above 8,000' on NW-N-NE aspects. All aspects that did not refreeze last night and remain unfrozen today will be prone to wet snow instability. Rain on snow on NW-N-NE aspects above 8,000' will be particularly prone to wet snow instability today. The vast majority of today's instability is expected to take the form of loose wet avalanches, however isolated wet slab and glide avalanches are not impossible.

    Widespread areas of deep wet snow are expected first thing this morning and all day today. Some weak and superficial snow surface refreeze may have occurred last night over the northern portion of the forecast area where cloud cover was thin. This weak and superficial refreeze is not expected to provide a workable window of quality travel conditions this morning. Evaluate areas of wet snow today for supportability. If in doubt, step off of equipment and observed the depth of body weight boot penetration into wet snow. Anything deeper than 8 to 10 inches is problematic. Avoid travel on or below slopes 35 degrees and steeper when deep wet snow conditions are present.

Avalanche Discussion

Observations made yesterday on Relay Peak (Mount Rose area) indicated that a poor snow surface refreeze had occurred in the area Thursday night. Deep wet snow conditions existed at the trailhead by 10:30 am. By 11:45 am, very few areas of supportable crust remained on E-SE-S aspects. Ski cuts on E-SE aspect test slopes at 9,100' produced loose wet avalanches at 11:25 am. On N aspects at 9,600', surface melt freeze conditions had only affected the top 2 to 3 inches of the snowpack. Snow below the surface crust had yet to undergo melt-freeze. Snow on upper elevation N aspects in this area is in poor condition to handle a rain on snow event.

Régions couvertes