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

Sunny conditions are expected for today.  LOW avalanche danger this morning will increase to MODERATE avalanche danger as daytime warming occurs due to a loose wet avalanche problem. 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Well below freezing temperatures with clear skies will have provided a good overnight refreeze of the snow surface.  As these surface crusts warm up and lose strength throughout the day, loose wet avalanche activity will become possible on all aspects and elevations.  Monday nights rain storm wetted the upper snowpack up to 1 to 2 feet deep with this layer slowly refreezing over time.  This wet snow will be of concern as the firm surface crusts warm and lose strength today.  Many areas will have firm exposed rain crusts that will pose travel concerns, especially this morning.  Higher elevation terrain exposed to the NE winds may not soften today at all.  In areas that lose supportability, loose wet avalanches could involve most of the wet snow beneath the surface crusts and be large in size.

    Monitor snow surface conditions.  Use slope angle to reduce loose wet avalanche hazards.

Avalanche Discussion

*  Several natural large cornice failures, loose wet avalanches, and a slab avalanche were observed yesterday on Donner Peak and Mt. Judah (Donner Summit area).  These looked to fail during Monday night's rain event and were all size D2 avalanches.  Cornice fall was also observed on Elephants Hump in the Carson Pass area.

*  Substantial rain on Monday night wetted the top 1-2' of the upper snowpack in the Donner Summit area.  This wet snow was capped by a surface crust that ranged from supportable to non-supportable.  Unsupportable crusts also existed in the Carson Pass area.  Small loose wet avalanches were easy to trigger on test slopes on E aspects in the late morning in the Donner Summit area.

Regions covered