Bulletin d’avalanche

Central Sierra Nevada

Sierra Avalanche Center
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Danger d’avalanche

Thu
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 weak refreeze last night and sunny warm weather today mean that the snow will quickly become wet and mushy.  Avalanches of wet loose snow will become possible on steep slopes. Once the snow becomes wet and unsupportable, it is time to move away from any slopes steep enough to avalanche.

Problèmes avalancheux

  • Loose Wet

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

    Warm overnight temperatures should have limited last night's refreeze. Some open slopes may have a thin surface refreeze in areas where the snowpack could radiate heat into the clear night sky. In areas with tree cover, little to no freeze may have occurred. Today's warm weather and intense April sun will quickly melt any refreeze that did occur. When that happens, deep, wet snow will exist on many slopes, and wet loose avalanches will become possible. As they move, these avalanches can entrain snow, making larger avalanches possible on long steep slopes. 

    If a window for supportable melt-freeze conditions exists, it will be short-lived and happen early today. Expect deep, soft, wet snow on most slopes once the day warms up. As soon as you start sinking through the surface crust into wet snow or see any signs of unstable wet snow like rollerballs or pinwheels, it's time to move onto low-angle slopes without steep slopes above them. 

Avalanche Discussion

  • Warm weather has allowed for cornice collapses and caused deep crevasse-like cracks to form behind cornices as they pull away from the ridges. It's best to give cornices a wide berth and spend as little time as possible on slopes below them.  
  • 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