Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 6 months ago.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

Highlights

Wet and unstable snow exists throughout the forecast area as rain on snow continues today.  Wet snow avalanches will be likely on all steep slopes with the potential for large and destructive avalanches occurring.  Dangerous avalanche conditions exist, consider avoiding avalanche terrain if traveling in the backcountry today.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3

    Wet and deep unstable snow exists throughout the forecast region with more avalanches expected today.  Travel will be difficult in the backcountry with rain, deep wet snow, and gale force winds.  Natural avalanches could occur this morning during the last of the higher intensity rainfall.   Avalanches could run long distances into treed or other areas thought "safe" for travel.  Consider avoiding travel in avalanche terrain and below avalanche run out zones if venturing out.

    Recent and continued heavy rain at all elevations will further erode bonds and weaken the snowpack.  Previous avalanche problems have all transitioned to wet slab avalanche problems.  Areas where unstable slabs of wind blown snow previously existed will have the potential for wet slabs to be triggered in wind loaded areas.  As rainfall amounts increase, NW-N-NE aspects where the buried Feb 10 facet layer exists will become more of a concern with uncertainty as to how these deeper weak layers will react.  Heavy rain will load the snowpack above these weak layers with the potential for large to very large avalanches occurring.  Any avalanches that involve the Feb 10 weak layer could propagate wider than expected, run long distances, and be large and destructive.  Wet loose avalanches are expected to be widespread on steep slopes on all aspects and elevations.  Many of our largest historical avalanches in the Greater Tahoe backcountry have occurred during rain on snow events.

Avalanche Discussion

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 continue to update that page as more information becomes available. 

Lower-elevation areas and sun-exposed slopes experienced significant snowmelt in late January and early February, exposing dirt, rock, and downed trees.  These hazards and obstacles now lie hidden beneath the recent snow. This creates a hazard situation similar to early-season coverage in some areas.  Additionally, deep open holes, open creeks, and ponded water linger in low-lying areas, especially below 8,000'. Today's rain may uncover some of these areas again. 

Regions covered