Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

MODERATE avalanche danger exists in near and above treeline terrain today with LOW danger in below treeline areas. Human triggered wind slab avalanches and loose snow sluffs will remain possible today. Carefully evaluate snowpack and terrain before committing to any slopes and use this information to avoid slopes where avalanche problems may exist.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    While most wind slabs may have become more difficult to trigger, some human-triggerable wind slab avalanches may remain possible in near and above treeline terrain today. These could include larger wind slabs left over from the storm that linger on NW-N-NE-E-SE-S aspects as well as newer wind slabs formed by NW and NE winds in the last 36 hours. These newer wind slabs should remain smaller and exist near ridgelines on E-SE-S-SW-W aspects. The most fragile wind slabs will exist in the places most exposed to wind-loading and in terrain like gullies, couloirs, unsupported slopes above cliffs, and other steep, complex, and wind-loaded terrain.

    Use clues such as blowing snow, cornice formations, and wind pillows to help identify recently wind-loaded slopes where unstable wind slabs may exist. Then use this information to plan a backcountry travel route that avoids the potentially unstable wind slabs and utilizes more sheltered terrain where better snow for recreation will exist.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    A cold, partly clear night means that the surface snow may have become less cohesive. Some loose snow sluffs could still remain possible on steep sheltered slopes. Most of these would occur where the coldest and least cohesive snow exists on NW-N-NE aspects. 

Avalanche Discussion

Yesterday a small human-triggered wind slab avalanche occurred on a SE aspect on Angora Peak. Several small loose snow sluffs occurred on steep slopes in the Job/Freel area, on Tallac, in the Cinder Cone area (east of highway 89), and on Angora Peak as well. In these areas as well as on Tamarack Peak and on Donner Summit, a "right-side-up" snowpack that went from soft snow at the top to more dense consolidated snow below existed in sheltered locations. In wind exposed areas in these places, large cornices existed above slopes and some wind slabs did remain. Tests and observations targeting these wind slabs in the Job/Freel area, on Tamarack, and on Tallac did not find lingering wind slab instability on wind-loaded test slopes. Snow surfaces ranged from wind-scoured to firm wind-packed snow to soft wind affected snow in exposed areas and soft unconsolidated snow in sheltered areas. 

Regions covered