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 throughout the forecast area at all elevations due to wind slab and storm slab avalanches.  Wind slabs will be possible in near and above treeline terrain and storm slabs in near and below treeline terrain.  Heightened avalanche conditions exist with human triggered avalanches possible today.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Moderate to strong SW winds yesterday created sensitive winds slabs that caused both natural and human triggered avalanches.  Winds began to shift towards the NE yesterday afternoon and have been in the moderate to strong range overnight.  This will cause wind slabs to be on most aspects in near treeline and above treeline terrain.  Human triggered wind slab avalanches large enough to bury a backcountry user (size D2) will remain possible today.  

    Look for recent avalanches, shooting cracks, cornices above slopes, blowing snow, or other wind created surface textures to identify where wind slabs may exist.  Avoid steep wind loaded terrain.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    Storm slabs will be unlikely today but not impossible in wind protected near and below treeline terrain.  Weaknesses observed yesterday within the new storm snow could continue into today with cold overnight temperatures and limited settlement of the new storm snow.  Loose dry avalanches, sluffing, will continue to be an issue in steep wind protected areas with the low density unconsolidated snow.  On NW-N-NE aspects in below and near treeline terrain, a layer of previous near surface facets is now buried below the last couple storms.  Reactivity has been limited with snowpack tests and informal observations, but that could change as the overlying snow settles, gains strength, and becomes a slab.

    Recent avalanche activity, cracking, collapsing, whumpfing, and/or snowpack tests can help determine where storm slabs may exist.  Avoiding steep slopes with signs of instability.   

Avalanche Discussion

* Wind slab avalanches were reported yesterday on Andesite Ridge (Donner Summit area) and the East Ridge of Tamarack Peak (Mt. Rose area).  Signs of wind slab instability were reported on Carson Pass.

* Loose dry avalanches, sluffing, was reported throughout the forecast area with new low density storm snow.

* The buried layer of previous near surface facets has been observed in below and near treeline areas.  Snowpack tests and informal observations have been limited in reactivity due to the lack of a cohesive slab above the weak layer.  

Regions covered