Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 12 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Avalanche danger is LOW for all elevations and aspects. Human triggered avalanches are unlikely, but far from impossible today. A very low probability, high consequence scenario lingers with a difficult to trigger large persistent slab avalanche concern in isolated areas above 8,700' on NW-N-NE aspects on slopes 37 degrees and steeper. Isolated small human triggered loose wet avalanches remain a possibility again today as warming continues.

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    Snowpack stability is improving, but data is still insufficient to entirely rule out the lingering concern for very difficult to trigger large persistent slab avalanches above 8,700' on NW-N-NE aspects on slopes 37 degrees and steeper. A weak layer of lower density rounds and rounding faceted snow crystals exists at the base of the recent storm snow in these areas and has been an instability issue in recent days. Given the nature of this type of avalanche problem, human triggered avalanche activity is possible on previously tracked slopes where the necessary trigger point has remained undisturbed. Areas around shallow buried or exposed rocks and along the base of cliff bands represent the most likely trigger points for this avalanche problem.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    As another round of rapid warming occurs today, human triggered loose wet avalanches will become possible on all aspects at all elevations following the formation of surface wet snow. The majority of instability is expected to take the form of roller balls and pinwheels. Small loose wet avalanches are possible in isolated areas on all aspects on slopes 37 degrees and steeper.

Avalanche Discussion

Recent observations from around the forecast area including those made yesterday on Incline Lake Peak (Mount Rose area) continue to indicate improving snowpack stability. The recent storm snow and associate weak layer of lower density old snow just below the old/new snow interface on NW-N-NE aspects above 8,700' continues to settle, gain strength, and adjust to the new snowpack load. Rapid warming conditions occurred yesterday with 1 to 4 inches of surface wet snow formation observed on all but the most heavily shaded N aspects on Incline Lake Peak by mid day. Wet surface snow along with melt water and snow falling off of trees was widespread on all aspects up to the summit at 9,760'. Evidence of surface wet snow instability was limited to natural roller balls and human triggered pinwheels up until departure from the area mid afternoon. Surface melt-freeze crust is expected to have formed in the vast majority of areas last night.

Regions covered