Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Wet snow instabilities continue with a thin overnight refreeze of the snow surface, a rain soaked upper snowpack, and very warm temperatures expected today.  Small wet snow avalanches are possible on all steep slopes.  The potential for large to very large avalanches on a deeper weak layer in the snowpack has become unlikely.  Move away from steep terrain if deep wet snow exists or you see signs of unstable wet snow.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Above freezing temperatures overnight occurred throughout the forecast region at most locations above 7000'.  Roller balls and pinwheels will be an indication that the snow surface is loosing strength and that larger wet loose avalanches could occur.  You could trigger a wet loose avalanche on steeper slopes where you sink into deeper wet snow.  If deep wet snow exists, move to a different aspect or move away from avalanche terrain.

    A superficial refreeze is expected overnight as radiational cooling of the snow surface occurred due to mostly clear skies.  As daytime warming occurs, surface crusts will quickly melt away exposing deeper wet snow below.  Travel conditions could be challenging today with thin firm rain crusts, deep wet snow, and uneven snow surfaces. 

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2–3

    Triggering a large to very large avalanche has become unlikely.  The Feb 10 weak layer has been fully wetted and is much closer to the snow surface as the snowpack has decreased dramatically from the Feb 24-25 rain event.  At this point, there have been no reported large avalanches failing on the Feb 10 layer from during or after the large rain event.  With a few exceptions, most recent snowpack tests are showing this layer gaining strength and becoming unlikely to propagate a fracture.  As the snowpack slowly refreezes, this layer will continue to gain strength.   

Avalanche Discussion

The recent rain event decreased snow depths dramatically, especially below 7,500' and on southerly aspects. This has created a hazard situation similar to early-season coverage in some areas.  Deep open holes, open creeks, and ponded water linger in low-lying areas, especially below 8,000'.

The avalanche that occurred on Tuesday, February 17, at the Frog Lake/Castle Peak area is a major blow to our community, and the human toll is immeasurable.  Our condolences go out to all those affected by this tragedy.  We have an avalanche observation posted here:  Perry Peak near Frog Lake/Castle Peak. We will update that page with any additional information that becomes available.

Regions covered