Central Sierra Nevada

Avalanche problems

• 

  Cornices

  • All elevations

  Likelihood

  Possible

  Size

  0

  For areas in the forecast area along the Sierra Crest, a supportable snowpack of 2' deep exists above 8000'.  Above 8500', the snowpack increases to 3'+ deep.  In the Mt. Rose area, above 8500' also has a 3'+ snowpack.  Below 7200'-7800' throughout the forecast area, the snowpack is shallow with a minimal amount of useable snow.  Many hazards and obstacles exist throughout the region including: exposed trees, rocks, bushes, open water, creek crossings, etc.  Firm rain crusts exist in wind scoured terrain throughout the area and could pose travel hazards.  

  Above freezing air temperatures are expected through this week with the chance of light rain up to 10,000' today.  Surface wet snow may form on all aspects and elevations with the possibility of small roller balls depending on rain amounts received.

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  2

  The ongoing deep slab avalanche problem continues to be unlikely but not impossible.  This problem is specific to the Mt. Rose area above 8500' on NW-N-NE aspects.  This is a low probability but high consequence event.  Most recent observations have shown that the previous weak basal facets have been gaining strength, beginning to round, are moist, and have become non reactive to most snowpack tests.  Although an observation from Saturday at 10,000' on a NE aspect, had ECT results that showed propagation was likely on the loose basal faceted layer. 

  The deep slab avalanche problem has a higher level of uncertainty than other avalanche problems.  Our typical snowpack tests and informal observations are not as reliable with a deep slab avalanche problem as with other avalanche problems.  Conservative route finding and decision making along with standard bc travel protocols are best practice.