Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Significant wind and new heavy snow during the storm have left large unstable slabs of drifted snow (wind slabs) on exposed near and above treeline slopes. In these areas, CONSIDERABLE avalanche danger exists and human-triggered avalanches are likely. In more sheltered below treeline areas, new heavy snow on top of older, lighter, weaker snow means MODERATE avalanche danger due to the possibility of storm slab avalanches.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Gale force SW winds have drifted snow onto the leeward NW-N-NE-E-SE aspects. These slabs of wind drifted snow will remain fragile today. Human-triggered wind slab avalanches will be likely and some natural wind slab avalanches may be possible. Exposed areas in near and above treeline terrain receive the most wind-loading and will hold the largest and most fragile wind slabs. However, some wind slabs may exist on a few below treeline slopes due to the strength of the winds. Wind slabs avalnaches could be large (D3) and dangerous today.

    Use clues like blowing snow, cornices above a slope, drifted snow, and other wind created textures to identify where wind slabs may exist. Avoiding these areas in favor of sheltered slopes without signs of the storm slabs mentioned below will provide a better safety margin for today. More consistent and enjoyable snow conditions may also exist on the sheltered slopes.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    The recent storm snow started out heavier than the old snow it accumulated on. Storm slab avalanches remain possible today since the additional weight of a person in the right spot may cause the storm snow to break away from the old snow. Storm slabs would be more fragile in the few areas where they rest on top of a weak layer of feathery snow (surface hoar). Steep open slopes in below treeline terrain hold the best potential for storm slab instabilities. As the snow settles this upside-down snow structure will consolidate.

    Look out for signs of recent avalanche activity, shooting cracks, or feeling lighter snow below denser snow in hand pits or while probing. These clues can help identify areas with potential storm slabs. Seeking out lower angle terrain without steeper terrain above it can provide quality snow and a good safety margin if there is any doubt about potential instabilities. 

Avalanche Discussion

* Yesterday observers found a mix of conditions with rain-soaked snow at lower elevations and new heavy snow at higher elevations. This new heavy snow rested on lighter older snow. 

* On Incline Lake Peak, the new snow rested on top of a thin layer of surface hoar in some areas and snowpit tests yielded potentially unstable results. 

* On Carson Pass, snowmobile slope cuts in near and below treeline terrain did not produce signs of instability before midday. Observers also reported significantly more blowing snow on the higher more exposed peaks in the distance. 

Regions covered