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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Highlights

Moderate avalanche danger exists throughout the forecast area at all elevations due to wind slab and deep slab avalanche problems.  Human triggered avalanches remain possible today.  Evaluate snow and terrain carefully, identify features of concern. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Strong NE/E winds will be able to transport snow today and form winds slabs on SE-S-SW-W-NW aspects near and above treeline.  The low density storm snow that fell yesterday will be easily transported with the strong NE/E winds.  Pay attention to top wind loading and cross wind loading of terrain features.  Look for blowing snow, new cornice formation, and wind pillows to help identify where wind slabs are developing.  Large cornices continue to exist along ridgelines, extra caution is advised around these hazards.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3

    Deep slab avalanches are becoming unlikely as our recent storm snow continues to settle and gain strength, and the snow below the Jan 9 rain crust begins to refreeze.  These deep slab avalanches are characterized by failure more than 3 feet deep in the snowpack and could be large wind slabs, storm slabs, or failures deeper in the snowpack to the Jan 9 or Dec. 15 rain crusts.  A widespread natural deep slab avalanche cycle occurred during the past storm cycle with many slopes avalanching.  No avalanches are thought to have happened with this avalanche problem since the main storm ended on Wednesday.  Large triggers in isolated areas remain the concern for today.   

     

Avalanche Discussion

Observations were received from Powderhouse (Luther Pass area), Wildflower Ridge (Donner Summit area), Deep Creek (Cabin Creek area), and Horse Meadows (Luther Pass area).  All areas received 4 to 8'' of additional snow yesterday.  Very little wind was reported with no wind slab development throughout the day with this new storm snow.  All areas reported signs of the previous storm snow settling, gaining strength, with formal and informal observations showing little to no signs of instabilities.  Many reports coming in of past avalanche activity throughout the forecast area from during or immediately after the storm cycle.  All of these avalanches are thought to have occurred sometime Wednesday or before.   

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