Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 6 years ago.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

Highlights

Little to no refreeze combined with warm weather and the potential for rain on snow means loose wet avalanches will be likely today. Some fresh slabs of wind drifted snow may also exist along the Sierra Crest above 8000 ft. Wet slabs also still warrant concern in some areas. The avalanche danger is CONSIDERABLE today. 

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    Yesterday's rain and warm temperatures should have allowed a thick layer of wet snow to form in most areas. This wet snow likely did not refreeze in most places due to warm overnight temperatures, some continued rain, and consistent cloud cover. Areas above 8000 ft where temperatures dropped below freezing and some of the precipitation fell as snow may have experienced a thin surficial refreeze. Periods of sun this morning combined with daytime warming and continued chances for afternoon showers will quickly melt through any refreeze allowing loose wet avalanches to occur on steep slopes again today. Some of these could entrain enough snow to bury a person. 

    Finding supportable snow will mean getting a very early start and heading to higher elevations. Even then the snow may not remain supportable for very long. As soon as the snow starts to get wet and lose its ability to support a person it is time to move to lower angle terrain or get off the wet snow. 

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Some sensors above 8000 ft along the Sierra Crest showed up to 5 inches of new snow accumulation since yesterday afternoon. SW winds also picked up during the night and may have grown strong enough to transport snow. This combination of wind and new snow could have allowed fresh slabs of wind drifted snow to form on upper elevation leeward aspects. Most of these wind slabs should remain small and inconsequential but a few of them could have grown large enough to pose a problem for backcountry travelers in the most heavily wind-loaded areas.

    Identify where wind slabs may exist using clues like cornices above a slope, drifts of new snow, or wind created surface textures. Use this information to adjust your travel plans to account for potentially problematic wind slabs. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Data indicates that the buried surface hoar layer is starting to assimilate into the snowpack and it is gaining strength. Still, with all of the uncertainty associated with forecasting wet slab avalanches, this problem will remain a concern for a little while longer. If a wet slab avalanche does occur it could involve enough snow to bury or injure a person.

    Using timing and terrain to avoid wet snow and/or steep terrain can help avoid wet slabs.

Avalanche Discussion

Observers on Jakes Peak and Mt. Tallac reported deep wet snow at all elevations before 10 am. The snowpack became unsupportable between 10 and 11 am.

On Mt. Tallac numerous recent loose wet avalanches had occurred and some of them involved enough wet snow to bury a person (D2).

Regions covered