Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
Open full map
Out of date — this forecast expired 10 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Considerable avalanche danger will exist as the next storm impacts our forecast area today and tonight.  Wind slabs will be likely above snow level on NW-N-NE-E-SE aspects near and above treeline.  Deep persistent slabs will be possible on NW-N-NE aspects above 9000' below treeline and above treeline.  Natural avalanches will be possible and human triggered avalanches will be likely.  Large destructive avalanches are possible today. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    As snowfall begins to intensify today at the higher elevations above snow level, wind slabs will quickly form and exist on NW-N-NE-E-SE aspects near treeline and above treeline.  Gale force winds gusting over 100mph above 8000' will have new snow available for transport.  Wind slab avalanches are expected to be likely today on slopes steeper than 35 degrees.  Wind slab avalanches on NW-N-NE aspects above 9000' will have the possibility of stepping down to the deep persistent slab weak layer and causing a very large and destructive avalanche.  Look for blowing snow, cornice formation, wind pillows and snow surface clues as to where wind slabs are forming.  Avoid terrain where active wind loading is occurring.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    The persistent slab avalanche problem we have been dealing with this season is now a deep persistent slab and buried anywhere from 3 to 5 feet deep in the snowpack.  This avalanche problem exists on NW-N-NE aspects above 9000' throughout the forecast area.  Recent snowpack tests continue to indicate that failure on this layer is possible.  Today and into tonight, we will see significant loading of heavy snow and rain to the snowpack and this deep persistent weak layer.  These deep persistent slabs could also be triggered by smaller wind slab avalanches that step down and cause failure on the persistent weak layer.  Large destructive and unsurvivable avalanches are possible today.

    Deep persistent slabs have unpredictable avalanche behavior.  These avalanches can be remotely triggered from any connected terrain.  Avalanche avoidance, cautious route finding and conservative decision making are critical today.  Avoid slopes 32 degrees and steeper and give runout zones a wider berth than normal as any avalanche may exceed path boundaries.

Avalanche Discussion

Observations were made and received from Andesite Peak (Donner Summit Area) and Tamarack Peak (Mt. Rose Area).  On Andesite Peak, 8200', rain soaked surface snow existed on top of a 8-10'' firm and strong rain crust.  Snowpack and informal observations showed a consolidated snowpack with no signs of instabilities.  On Tamarack Peak, 9900', strong SW winds were blowing snow and forming small wind slabs into the mid afternoon.  Snow surface conditions were a mix of wind effected snow, wind scoured areas, and wind crusts.  Ski cuts in this area did not show signs of instability.   

Regions covered