Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

New snow, wind, and a chance of rain will make triggering avalanches possible again today. Watch out for areas where wind-blown snow piles up on open slopes near ridges and gullies and places where rain or heavy snow falls on lighter snow today. The avalanche danger will increase tonight and tomorrow as more intense wind and snow hit the area.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    A party reported a small wind slab avalanche yesterday. Expect similar conditions today as more wind and moderate snowfall impact the area. Slabs of wind-drifted snow will most likely exist on open slopes near ridges, gullies and couloirs, and cross-loaded areas near and above treeline. The largest and most fragile wind slabs should exist on NW-N-NE-E-SE aspects. However, wind slabs may form in unusual places due to the winds having a more southerly direction. People can trigger wind slab avalanches large enough to bury them today. 

    As the snowfall and wind intensify tonight, wind slabs will become more widespread, easier to trigger, and larger.

    Look closely for any signs of wind loading on a slope before committing to it. Blowing snow, cornices above a slope, snow drifts, and smooth hollow sounding snow can all indicate the presence of wind slabs. Focusing on areas sheltered from the wind represents one tactic that could help mitigate the risk of encountering an unstable wind slab and increase the chances of finding consistent soft snow.

    (1/3/2023)

    Small wind slab on Red Lake Peak

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Rising snow levels could lead to upside-down storm snow by this afternoon. The heavier layer of storm snow could break free from the lighter snow in some places resulting in storm slab avalanches. Most of these would be small since today's snowfall amounts are forecasted to remain modest, but they may get large enough to cause problems in places that receive the high end of forecasted snow amounts. In addition to possible storm slabs, rain could fall on new storm snow as the snow levels rise. If this happens, expect to see some wet loose snow instabilities. 

    Strom slabs will become larger and more widespread as the snowfall intensifies tonight and tomorrow.

    As conditions change today, watch for signs of unstable snow, like shooting cracks, feeling heavy snow on top of lighter snow, or rain on snow. Moving lower-angle slopes that are not below steeper slopes can help avoid areas with potentially unstable snow. 

Avalanche Discussion

 

  • Intense blowing snow was reported along ridgelines across the forecast area yesterday. One party witnessed a small wind slab avalanche that failed naturally on Red Lake Peak. 
  • "Punchy," upside-down conditions have been reported around the forecast area at all elevations on sheltered and exposed terrain. While this has made travel trickier, no signs of instability have been reported associated with this slightly upside-down layering.
  • Recent winds have scoured away the recent storm snow and exposed a firm icy rain crust in a variety of near-treeline and above-treeline areas, especially below 9,000'.

Regions covered