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 continues due to a persistent slab avalanche problem.  Human triggered avalanches remain possible at all elevations.  Evaluate snow and terrain carefully, identify features of concern.

Problèmes avalancheux

  • Deep Persistent Slabs

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

    Human triggered persistent slab avalanches remain possible on NW-N-NE-E aspects at all elevations.  On Tuesday, we had a natural avalanche occur on this layer in the Carson Pass area.  In other areas, snowpack tests continue to show that this layer is weak, and if triggered, could propagate and cause an avalanche.  Areas near treeline and below treeline seem the most likely places for this weak layer to exist and be reactive.  The facet layer is moist to wet in many areas from the recent rain and warm temperatures and is expected to gain strength as the snowpack refreezes. 

    Look for collapsing, cracking, or whumpfing of the snowpack.  Start zones could be low or mid slope in near treeline or below treeline terrain.  Practice safe travel protocols and avoid avalanche run out zones.  These avalanches are capable of injuring or burying a backcountry user.

Avalanche Discussion

*  Consistent unstable snowpack test results yesterday on Tamarack Peak (Mt. Rose area) on a buried layer of facets.  These observations were made on NW-N aspects in near treeline and below treeline terrain.

*  On Tuesday, a natural triggered persistent slab avalanche occurred on Elephants Hump in the Carson Pass area.  Widespread signs of instability with collapsing, cracking, and whumpfing of the snowpack were also observed.

* NW-N-NE aspects above 8,000' in the Mt. Rose area and along the Sierra Crest north of Emerald Bay hold the best snow coverage at 2 to 4+ feet. Overall less snow cover exists south of Emerald Bay. Areas of decent coverage exist above 8,500' on NW-N-NE aspects in the Carson Pass area.  Coverage decreases on all other aspects, with large areas of bare ground on the vast majority of southerly aspects at all elevations.

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