Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 13 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Near treeline and below treeline, MODERATE avalanche danger continues on NW-N-NE aspects on slopes 32 degrees and steeper due to lingering persistent slabs.

Human triggered avalanches remain possible. Shallow covered rocks, logs, and stumps are an additional hazard to backcountry travelers. Impact with rocks or trees while caught in an avalanche can greatly increase consequences.

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Just over two weeks have past since the most recent significant snowfall event and persistent slab instability continues. While some small and very gradual improvement in stability has occurred over that time, it does not negate the fact that human triggered avalanches remain possible. The problematic faceted Dec 7 persistent weak layer remains widespread on NE wind protected slopes near treeline and below treeline on NW-N-NE aspects. Evidence of instability is still encountered on a near daily basis by backcountry travelers. Snowpit data continues to point out the current instability. Avalanche avoidance through travel on sub 32 degree slopes without steeper slopes above remains the best way to mitigate the hazard.

Avalanche Discussion

Observations made yesterday near Grouse Rocks (Ward Canyon area) pointed towards two rather interesting conclusions regarding the persistent slab instability that exists near treeline and below treeline on NW-N-NE aspects. No obvious signs of instability were observed while on tour in the area and snowpit data revealed increased difficulty in triggering collapse and subsequent propagation along the faceted Dec 7 persistent weak layer. This indicates that some improvement in stability has occurred in this area. Despite the stability improvement, snowpit data also showed that two different N aspect below treeline slopes with ski tracks on them still had the ability to collapse and propagate along the Dec 7 persistent weak layer. This indicates that if the right trigger point is found on the slope, the necessary snowpack ingredients for a human triggered avalanche remain present.

Rocks, logs, and stumps lurk below the snow surface. The ability of the snowpack to keep a person supported above these hazards remains variable and can change greatly over short distances. Travel accordingly to minimize the risk of injury.

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