Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 11 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Avalanche danger remains low on all aspects and elevations.  Isolated areas of instability may exist.  Normal caution is advised.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    0

    Winds shifted back to the SW yesterday afternoon and will be in the moderate to high range above 8000' today.  This may cause some blowing snow and small wind slab development near and above treeline on exposed ridges and peaks.  These should remain small and isolated and not pose a risk for backcountry users today.  Look for visible blowing snow, cornice formation, wind pillows, and snow surface scouring as clues to identify suspect slopes.

    Normal caution means exercising basic travel techniques.  Travel one at a time in avalanche terrain, regroup in safe spots out of the avalanche path, avoid travel near terrain traps, and practice good communication within your group.

Avalanche Discussion

A small wind slab avalanche was skier triggered off of the top of Deep Creek Peak yesterday.  This occurred on a NE aspect, at 8400', directly off ridge top, with a crown height of 2 to 6'' deep. 

Other observations from Deep Creek showed a uniform and consolidated snowpack.  2 buried surface hoar layers were observed (1/9 and 1/13 layers) and both were found to be rounding and not reactive to snowpack tests.  4 to 6'' of unconsolidated snow existed on northerly aspects.

Observations from Stanford Rocks (Ward Canyon area) showed similar conditions.  Snowpack tests targeting the 1/9 buried surface hoar layer showed this layer to be gaining strength and not reactive.  The recent 1/23 rain crust is present below 8000' and only covered by 3-4'' of snow at lower elevations.  This crust is mostly supportive but on southerly aspects it is more variable and breakable in locations.  No signs of instabilities existed in this area.

What happened to the deep persistent weak layer?

In early to mid January, up to 3 separate surface hoar layers formed and were buried by subsequent storms on N-NE-E aspects near treeline and below treeline.  These buried surface hoar layers are currently buried 1.5 to 4.5 feet deep in the snowpack.  A widespread persistent slab avalanche cycle occurred Jan 5 through Jan 19 on these weak layers.  Many slopes have been "cleaned out" by already avalanching, or the surface hoar has been collapsed or compressed and has gained strength.  Targeted observations and snowpack tests have shown that these layers, in the majority of locations, are no longer reactive and have assimilated into the snowpack.  No avalanche activity has been associated with these buried surface hoar layers since Jan. 19.

This deep persistent avalanche problem has become unlikely and has been removed as an avalanche problem.

Regions covered