Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

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

Points saillants

A relatively short time period of supportable snow surface conditions is expected this morning before wet snow avalanches become a concern. Once the superficial snow surface refreeze melts away, wet loose avalanches are possible. For travel in avalanche terrain, start early and end early before areas of deep wet snow develop.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    A weak to decent superficial snow surface refreeze is expected to have occurred last night from the radiational cooling of the snowpack under clear skies. The most supportable refreeze will have occurred on open slopes away from exposed rocks and trees. Refreeze may not have occurred under the forest canopy. Mid and upper elevation air temperatures in the low 40s to low 50s at sunrise this morning will aid in quickly melting whatever amount of superficial refreeze occurred last night. Once the superficial snow surface refreeze is melted away, the residual deep wet snow below it becomes exposed. This opens the door for a wet loose avalanche problem.

    Wet loose avalanches are possible once the snow surface becomes unsupportable or you can sink past about ankle deep into wet snow. Consider avoiding avalanche terrain or at least slopes steeper than about 35 degrees when unsupportable or deep wet snow conditions exist.

    (4/26/2023)

    A weak and superficial snow surface refreeze capping residual deep wet snow. Once the thin superficial refreeze melts away, wet loose avalanches are possible. Castle Peak, Donner Summit area, CA.

    Photo: SAC

Avalanche Discussion

  • Cornice collapses continue to occur. Minimize exposure time on slopes below cornices or avoid them altogether. While on the ridgetops keep exposed rocks or trees between you and the cornice edge whenever possible.
  • Glide cracks have also opened up on some steep slopes in rocky areas. The exact timing of glide crack avalanches is notoriously difficult to predict. Due to the uncertainty, consider avoiding travel on or below slopes with glide cracks.

Régions couvertes