Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Human triggered very large avalanches remain possible today.  While these avalanches have become harder to trigger, the consequences remain extremely high.  Conservative terrain choices utilizing less steep slopes remain the best way to manage this avalanche problem. 

Avalanche problems

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–4

    After a 5 day period of no avalanches reported on the Dec 1 persistent weak layer last week, we received a large storm cycle with 3 to 5' of new snow loading our snowpack by Monday morning.  We have reports of additional avalanches that appear to have failed on the Dec 1 weak layer during or towards the end of the storm cycle.  The Dec 1 weak layer is now buried 4 to 6 + feet deep in the snowpack and is most prominent on NW-N-NE aspects.  While triggering this deep weak layer is becoming more difficult, the consequences remain extremely high.  Any avalanches this big and deep would be catastrophic.  These avalanches could be remotely triggered from long distances away, could require large loads to initiate, or be started from trigger points in complex terrain or shallow areas of the snowpack. 

    Managing a deep slab avalanche problem comes down to avalanche avoidance until this problem goes away.  Utilizing sub-30 degree terrain and/or recreating on SE-S-SW aspects where this problem does not exist are two strategies to use and still get out and enjoy the new snow .    

    (12/12/2022)

    Very large avalanche crown in Hourglass Bowl, Tamarack Peak, NV.

    Photo: Public

Avalanche Discussion

  • Several large avalanches have been reported throughout the forecast area thought to be deep slab avalanches failing on the Dec 1 weak layer during or at the end of the Dec 9-12 storm cycle.
  • A brief period of moderate to strong NE/E winds last night may have produced some light wind scouring and blowing snow on the highest and most wind exposed terrain.  Limited wind slab development is expected.
  • With improving visibility, there should be an opportunity to see if any deep persistent slab avalanches occurred naturally during the recent storm. If you see a large crown, please submit an observation with a photo and location info.

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