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

Loose wet avalanches will become possible today as daytime warming and increased solar radiation occur at all elevations.  A deep slab avalanche problem is unlikely, but not impossible in near and below treeline areas.  MODERATE avalanche danger continues.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Loose wet avalanches will become possible with increased solar radiation and daytime warming.  The potential for avalanches will start in the late morning hours and last through the afternoon.  Increasing cloud cover today could limit loose wet avalanche activity on solar aspects in some areas.  Intense March sunshine with even partly sunny skies could still make the surface snow wet and unstable.

    As the surface snow becomes wet and punchy, it's time to move to different aspects.  Roller balls and pinwheels may be indicators of the potential for larger loose wet avalanches to occur.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2

    Deep slabs exist in isolated areas of the forecast region.  Weak layers of faceted snow and crusts formed during our dry February and are now buried under this recent storm snow.  A natural deep slab avalanche cycle occurred during the large storm event on last Sunday along with 2 human triggered avalanches on this weak layer, the last avalanche reported on Thursday.  Some snowpack tests continue to show that propagation is possible on this weak layer with no other signs of instabilities or other recent avalanches reported.  This avalanche problem is unlikely on a regional scale, but by no means impossible.

    This deep slab avalanche problem exists on NW-N-NE aspects in near and below treeline areas.  Large triggers, steep complex terrain, or unsupported slopes may be the most likely areas for avalanche potential.  Avalanches involved with this weak layer would be large and destructive. 

Avalanche Discussion

Further investigation of the reported slab avalanche on Fireplug, in the Mt. Rose area, occurred yesterday.  It was found that this was a wind slab avalanche that failed post storm sometime on early Thursday.  This was reported to be a natural avalanche with several other similar small wind slab avalanches in the immediate area.

Reactive buried facets were found on Angora Peak (Echo Summit area) yesterday.  The facet layer was buried 3 to 4' deep in this area.  Extended column tests showed that propagation is still possible at this location.

Surface hoar has been reported in the Echo Summit, Luther Pass, Ward Canyon, Ebbetts Pass, and Donner Summit areas.  It is likely that this surface hoar will be destroyed by winds and warming temperatures ahead of the next snowfall event, but continued monitoring is warranted. 

Regions covered