Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

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

Sunny and warm conditions are expected today with the chance of showers and thunderstorms this afternoon.  Loose wet and wet slab avalanche problems will continue to be a concern.  MODERATE avalanche danger will exist as rapid daytime warming occurs.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Cooler air temperatures overnight will allow for a better refreeze of the snow surface than yesterday.  Full sun this morning with rapid warming will again allow the snow surface crust to melt and become wet and punchy into the mid-day.  Loose wet avalanches will become possible on all aspects and elevations as the snow surface becomes wet and loses strength.  Any rain showers this afternoon could increase loose wet activity.  Avalanches large enough to injure or bury a backcountry user are possible today.

    Avoid steep terrain in areas where the surface crust is no longer supportable.  E-SE-S aspects will melt the quickest, followed by varied rates on SW-W-NW-N-NE aspects.   Timing will be important before snow conditions deteriorate. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    The March 24 buried surface hoar layer is 1 to 2 feet below the snow surface on open NW-N-NE-E aspects at all elevations.  This snowpack structure along with our current weather conditions could allow for wet slab avalanches to occur as meltwater percolates down to the buried surface hoar layer.  A large natural wet slab avalanche occurred in Desolation Wilderness on Sunday.  These wet slab avalanches are notoriously difficult to forecast with a high degree of uncertainty.

    Timing and terrain choices can help to limit exposure to these wet slab avalanches.  Get an early start!  Avoid deep wet snow and steep terrain later in the day as the snowpack loses supportability.  

Avalanche Discussion

A large natural wet slab avalanche was reported from Desolation Wilderness, thought to have occurred sometime on Sunday.  This avalanche was on a NE aspect, mid-slope, with wide propagation.  It occurred off of the ridge between Pyramid Peak and Mt. Price.

Observations from Mt. Tallac showed a poor overnight refreeze.  Soft snow conditions existed by mid-morning on areas with direct sun.  By 11:30am, mostly wet snow existed at all elevations with some occasional firm snow in shaded locations.  Monitoring the March 24 buried surface layer showed that this layer has been thoroughly wetted and did not respond to snowpack tests. 

Red Lake Peak on Carson Pass showed a good overnight refreeze of the upper snowpack.  Strong melt freeze crusts up to 8'' thick provided good travel conditions in the mid-morning hours.

Regions covered