Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

CONSIDERABLE avalanche danger will exist at all elevations due to continued snow and wind throughout the forecast region.  Wind slab avalanches will be likely in near and above treeline areas with storm slab avalanches likely in near and below treeline areas.  Cautious route finding and conservative decision making will be required today to avoid these avalanche .problems.

Avalanche problems

  • Wind Slabs

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

    Wind slabs continue to build with the additional storm snow from last night and continued SW winds.  Wind slab avalanches will be likely today in near and above treeline areas on NW-N-NE-E-SE aspects.  Strong to gale force SW winds are expected to continue throughout today transporting snow.  Wind slabs will be stacked on top of previously formed wind slabs which could make for large avalanches (size D2) that could occur.  Natural wind slab avalanches are possible with human triggered wind slab avalanches likely in these areas.  

    Look for blowing snow, cornice formation, and wind pillows.  Cornices will be built out and fragile and could break well back of ridgelines.  Avoid travel on steep wind loaded slopes and slopes below large cornices.  

  • Storm Slabs

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

    Storm slab avalanches could occur on all aspects in near and below treeline areas.  In some locations, over 2 feet of recent storm snow has accumulated from these last 2 storms.  Weaknesses within this new storm snow, at the new snow old snow interface, or between these storm layers could cause bonding issues that lead to avalanches.  Natural storm slab avalanches could occur as well as human triggered avalanches.

    Look for cracking or any signs of slab characteristics within the new and recent storm snow.  In areas where storm slabs do not exist, loose dry sluffing will be expected in steep terrain.  If signs of instability are encountered, step back to below 30 degree terrain with no overhead hazards.  

Avalanche Discussion

* Snowpit observations have noted that faceting has started to weaken the snowpack around the buried Feb 19 rain crust in the upper portion of the snowpack on some NW-N-NE aspects. New loading of this developing weak layer is not expected to be enough to cause failure.

* Wind slabs continued to form throughout the day yesterday with the continued strong to gale force SW winds.  As these wind slabs grew in size, propagation started to occur in the afternoon.

Regions covered