Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Sat
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Calm and warmer weather is expected for the next several days.  Avalanche activity has become unlikely throughout the forecast region.  Isolated instabilities could still be encountered, especially on the eastern side of the forecast region where a weak and shallow snowpack exists.  Travel with a mindset and actions that will minimize the consequences of triggering an avalanche unexpectedly. 

Avalanche problems

  • Persistent Slabs

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

    The persistent slab avalanche problem that has been with us for most of our season is becoming unlikely.  These weak layers can still be found where a shallow and weak snowpack structure exists-mainly in the eastern part of the forecast region.  All of these layers have now been tested multiple times with recent storm loading and have not been reactive with avalanche activity.  The Jan 2 PWL (buried surface hoar, facets, and/or near crust facets) has become unreactive with no known avalanches occurring since Jan 18.  The Dec 19 rain crust and the basal facet/depth hoar layers were involved in a couple avalanches on Dec 20 and then again with multiple avalanches that stepped down to these weak layers in the Jan 13-14 storm cycle.  Unfortunately, these weak layers will continue to exist in areas with a weak and shallow snowpack for some time until our snowpack gets deeper and gains additional strength.  There is also the potential that these weak layers could reactivate if a large loading event where to happen in the future.

    An isolated large avalanche could still occur in areas where the snowpack remains weak and shallow.  On a regional scale, this represents a small portion of the forecast area.  Wide safety margins and best practice travel protocols remain good strategies for backcountry travel.

Avalanche Discussion

Multiple avalanches were reported yesterday that occurred either at the end of the Jan 19-22 storm cycle or during the more recent Jan 24 rain and high elevation snow storm.  These ranged from loose wet, cornice collapses, and wind slab avalanches.

The Jan 24 surface hoar layer has been found to be buried in some areas above 9000' under 1-2 inches from Wednesday’s storm snow.  This layer could be preserved in these areas until our next storm, but is not currently a concern with the minimal snow load.  Wednesday's rain event is thought to have destroyed most of this surface hoar layer up to 8000-9000'.

Regions covered