Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 12 years ago.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

Highlights

Pockets of MODERATE avalanche danger linger above 8,700' on NW-N-NE aspects on slopes 37 degrees and steeper due to persistent slabs. For all other areas, avalanche danger is LOW. A low probability, high consequence scenario has formed with difficult to trigger large avalanches remaining possible in specific areas. Thoughtful deliberate terrain selection is the key to hazard avoidance.

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    Difficult to trigger large avalanches are an ongoing concern 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 the main instability issue over the past several days. Given the nature of the weak layer and this type of avalanche problem, human triggered avalanche activity remains 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 air temperatures warm, increasing amounts of wet surface snow form, and increasing amounts of snow falls off of rocks and trees, natural and human triggered loose wet avalanches will become possible on all aspects at all elevations. The majority of instability is expected to take the form of roller balls and pinwheels, but small to medium size loose wet avalanches are possible in isolated areas.

Avalanche Discussion

Recent observations from around the forecast area indicate that the recent storm snow continues to gain strength in the majority of areas. However, a lower density layer of old rounds and rounding faceted snow crystals now buried 2 to 3 feet deep just below the old/new snow interface remains problematic in specific areas. Avalanche activity on slopes 38 degrees and steeper on north aspects off sub ridges on either side of Relay Peak (Mount Rose area) on Feb 7 and Feb 8 along with recent snowpit data from Carson Pass and Waterhouse Peak (Luther Pass area) point to an ongoing persistent slab instability issue on NW-N-NE aspects above 8,700'. Otherwise, generally good stability has been observed over the past few days on E-SE-S-SW-W aspects above 8,700'. Generally good stability has also been observed on all aspects below 8,700' where the weak layer in question was destroyed by rain.

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