Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

High avalanche danger will exist throughout today due to wind slab, storm slab, and loose wet avalanche problems.  Very dangerous avalanche conditions exist with natural avalanches likely and human triggered avalanches very likely.  Travel in avalanche terrain is not recommended.  Conditions will further deteriorate tonight as an atmospheric river brings additional heavy rain and high elevation snow to our area.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2

    Wind slabs will be very likely on NW-N-NE-E-SE aspects in near and above treeline terrain as additional snow and gale force SW winds impact our area today.  Wind slabs could also develop on other aspects, in unusual areas below treeline, and much farther downslope than normal with wind gusts forecasted to be 130mph over the higher ridges.  Large and fragile cornices exist along ridgelines and should be avoided.  Whiteout conditions with limited visibility is expected today.

    Travel in avalanche terrain is not recommended.  Avoid wind loaded terrain and runout zones below wind loaded terrain.   

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1

    Storm slabs will continue to develop on all aspects in protected near treeline and below treeline terrain as snowfall continues.  These storm slabs could have an upside down storm snow structure as temperatures fluctuate through this storm cycle.  Clues such as snow surface cracking may indicated storm slab development.  Travel in or around avalanche terrain is not recommended.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Areas of rain on snow today will be prone to loose wet avalanche activity.  Snow level is forecasted to remain near or below 6500' through today.  If snow levels rise more than forecasted loose wet avalanches could become more widespread.  Loose wet avalanche activity today could be either natural or human triggered.  Terrain traps such as creek beds and road cuts could increase the depth of avalanche debris associated with otherwise small loose wet avalanches.

Avalanche Discussion

Observations were made and received yesterday from Carpenter Ridge (Independence Lake area), Waterhouse Peak (Luther Pass area), and Andesite Peak (Donner Summit area).  Heavy amounts of blowing snow were observed at all locations throughout the day with strong to gale force SW winds.  Several test slopes at Carpenter Ridge and Waterhouse Peak did not show signs of instability.  Many areas of cornice failures were observed along ridgelines in the Carpenter Peak area and also the Donner Summit area.

Regions covered