Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Snowfall amounts and avalanche danger will vary greatly around the forecast area today. Adjust terrain choices and route selection according to localized conditions. Near and above treeline on NW-N-NE-E-SE-S aspects on slopes 35 degrees and steeper, avalanche danger could range from LOW danger to CONSIDERABLE danger based on the size of newly formed wind slabs. Below treeline, avalanche danger could range from LOW danger to MODERATE danger on all aspects on slopes 35 degrees and steeper based on snowfall.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    In some locations around the forecast area, new wind slabs will build this morning in near treeline and above treeline terrain on NW-N-NE-E-SE-S aspects. The presence or absence and size of wind slabs will vary greatly today as new snowfall amounts vary widely across the forecast area. In the areas of greatest snowfall, wind slabs 1 to 2+ feet deep are possible today. This is certainly large enough to bury or injure a person. In these localized areas of higher snowfall, human triggered avalanches are possible to likely today and natural avalanches are possible. This avalanche problem may not exist in areas of minimal snowfall today.

    Be aware of highly localized avalanche conditions today and avoid potentially unstable wind slabs where they have formed. Use clues such as blowing snow, recent avalanche activity, cornice formations, wind pillows, and human triggered snow surface cracking to help identify areas to avoid.  

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    In localized areas where new snow amounts exceed 6 inches today, storm slabs could form in wind protected areas on all aspects below treeline on slope 35 degrees and steeper. Evaluate localized conditions for new snow amounts and the potential for unstable storm slabs. Clues such as human triggered snow surface cracking, test slope failures, and unstable snowpit test results in wind protected areas below treeline are helpful in identifying potentially unstable storm slabs. This avalanche problem may not exist in areas of minimal snowfall today.

Avalanche Discussion

Observations made below 8,000' yesterday on Lincoln Ridge (Yuba Pass area) and near Blackwall on Donner Pass revealed widespread unstable wet snow conditions on all aspects. Loose wet avalanches were easily skier triggered on slopes 40 degrees and steeper. A few small to medium size loose wet avalanches were noted to have occurred naturally. Snow surface refreeze from the night before varied from poor to decent and was melted by mid to late morning in most areas. With the below freezing air temperatures last night and today, snow surface refreeze is expected to have occurred with new snow deposited on top of crust at all elevations on solar aspects and as well as on northerly aspects below 8,000' to 8,500'.

Regions covered