Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

New snow and wind will continue to create areas of blowing and drifting snow that deposit as unstable slabs near ridgelines and in gully features. Rapid snowfall rates this morning may contribute to instability within the new snow. Exercise increased caution and consider avoiding avalanche terrain in areas where signs of unstable snow are present.

Avalanche problems

  • Wind Slabs

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

    Signs of unstable wind slabs and wind slab avalanches have occurred several days in a row. Winds out of the SW have continued to drift low density snow and deposit it near ridgetops and into gully features. Avalanche concerns remain ongoing for areas where this drifted snow has deposited as a cohesive wind slab. Additional new snow this morning along with SW winds will contribute to another round of wind slab development today.

    Wind slabs remain most widespread in near treeline and above treeline terrain across NW-N-NE-E-SE-S aspects. Identify the areas of concern where wind drifted snow is depositing, mainly near ridgetops and gully features. Slopes below cornice features are highly suspect. Consider avoiding travel in areas with obvious wind loading, snow surface cracking, or recent avalanches.

    (3/7/2023)

    Intentionally triggered wind slab avalanche on a SSE aspect test slope. Full width (R5) propagation of 75'. Tamarack Peak, Mount Rose area, NV

    Photo: SAC

  • Storm Slabs

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

    A few hours of moderate to high intensity snowfall this morning may lead to the development of new storm slabs up to one foot thick in wind protected areas on all aspects. The potential exists for an isolated, deeper storm slab avalanche to occur on SE-S-SW aspect terrain where weakness exists at a faceted melt-freeze crust that was buried on March 4 and is now around 1 to 3 feet below the snow surface.

    If you trigger snow surface cracking in wind protected areas, snowpack collapse, whumpfing noises, or see unstable snowpit test results, storm slab instability is present. Consider avoiding avalanche terrain in areas where signs of unstable storm slabs exist.

Avalanche Discussion

  • SW winds have remained ongoing with drifting of new snow observed daily in near treeline and above treeline terrain.
  • Several wind slab avalanches size D1 to D2 occurred yesterday in various portions of the forecast area.
  • Reports of snowpack collapse and whumpfing were received Monday from two separate locations on southerly aspects in the Mount Rose zone. Isolated whumpfing was again reported yesterday in this zone, likely on the March 4 crust/facet layer. Other observations targeting this layer yesterday did not reveal signs of instability.

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