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 will exist today throughout the forecast region.  Human triggered wind slab and storm slab avalanches will be possible at all elevations. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Large wind slabs and cornices that formed during the recent storm cycle may still be reactive today in near and above treeline terrain on NW-N-NE-E-SE aspects.  In addition, moderate to strong SW/W winds today and tonight will continue to build fresh new wind slabs.  Substantial amounts of storm snow is available for transport and these new wind slabs will continue to build in size today.

    Look for blowing snow, cornice formation, wind pillows, and snow surface clues as to where wind loading is occurring.  Give yourself a wide safety margin around wind loaded terrain and large cornices.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    Storm totals range from 2 to 3' + of new snow over a 36 hour period.  Continued cold temperatures will slow down the settlement process of this new storm snow.  While most data suggest the recent storm snow is gaining strength, 1 report from yesterday showed propagation results from ECT's at the old snow/new snow interface along with a whumpf in the area.  Uncertainty exists about this weak layer and how widespread it could be.  Storm slabs will continue to be possible on all aspects in non-wind loaded terrain near and below treeline.

    Look for cracking around skis or any signs of cohesion in the recent storm snow.  Whumpfing sounds would indicate that a weak layer is buried, reactive, and has the potential for remote triggering.  Loose dry sluffing will be possible in steep terrain where no storm slab exists and could pose travel concerns.

Avalanche Discussion

*  On Andesite Peak (Donner Summit area), several natural wind slab avalanches were observed that occurred during the storm and were partially covered up by additional snow.  Signs of additional wind slab instabilities were limited.  Active wind transport was occurring and building fresh new wind slabs during the day.

*  A whumpf was reported on a SE aspect near Poulsens Peak (Squaw Valley area) with ECTP results at the old snow/new snow interface.  2 to 2.5' deep, the potential weak layer could be buried surface hoar and/or near crust facets.

*  2 to 3' of recent storm snow was reported from yesterday from multiple locations.  

Regions covered