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 may form on sun-exposed near and below treeline E-SE-S-SW-W aspects as well as on some above treeline SE-S-SW aspects due to the possibility of loose wet snow instabilities. Wet surface snow and small instabilities like pin wheels and roller balls can indicate that loose wet avalanches have become possible. The amount of warming that actually occurs today will dictate how widespread these possible wet snow instabilities may be. 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    A mostly clear cold night should have allowed the wet snow that formed yesterday to refreeze during the night. Sunshine and warm temperatures today may allow some some loose wet snow instabilities to become possible this afternoon as the snow warms back up on steep sun exposed SE-S-SW aspects and some lower elevation E and W aspects. Small pinwheels, roller balls, and point release avalanches (sluffs) should represent the majority of the loose wet instabilities, but a few could entrain enough snow to cause issues for backcountry travelers since they could involve most of the snow above the uppermost rain crust. The north winds and clear skies should limit these wet snow issues to the most sun exposed aspects. If the stronger north winds or lower day time highs than forecasted occur, these wet snow instabilities will be more isolated and smaller. If weaker north winds and higher temperatures than forecasted occur, these wet snow instabilities could become more widespread and larger. 

Avalanche Discussion

Yesterday observations on Andesite Ridge in the morning and on Angora Peak in the afternoon showed 10 to 15 inches of unconsolidated soft snow sitting on top of a thick rain crust on the sheltered northerly aspects. On more exposed near and above treeline slopes on all aspects, a mix of firm icy crusts and wind scoured surfaces existed on Andesite Peak. Snowpit tests, ski cuts on test slopes, and general observations did not reveal any signs of instability in these areas where the snow surface remained cold. In the afternoon on the lower elevations of Angora Peak, ski cuts on steep slopes triggered loose wet snow instabilities like point releases and pinwheels. Across the Lake where less cloud cover existed yesterday, more widespread wet snow instability existed. Large loose wet snow avalanches resulted from ski cuts on southerly facing slopes on Slide Mountain in the Mt. Rose backcountry. Reports indicated that these loose wet avalanches entrained all of the most recent snow and slid on the rain crust 12 to 16 inches below the surface.  

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