Central Sierra Nevada

Problemi valanghivi

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  1

  Strong SW winds yesterday began transporting snow and forming new wind slabs and cornices.  SW winds continued overnight and are forecasted to remain strong to gale force through today.  New unstable wind slabs are expected in near and above treeline terrain on NW-N-NE-E-SE aspects.  These wind slabs could be large enough to injure or bury a backcountry user. 

  Look for blowing snow, new cornice formation, and snow surface scouring as clues to where new wind slabs will exist.  Avoid travel below large cornices and steep wind loaded terrain.

   

   

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Unlikely

  Dimensione

  2

  Buried surface hoar below the 12/6-12/8 storm snow has been responsible for 1 snowboarder triggered avalanche on Monday and thought to be responsible for a handful of natural avalanches near the end of the storm cycle on Sunday.  This weak layer has been found in isolated areas and is thought to have only been reactive in the Donner Summit area.  Continued snowpack tests and observations have found this layer to be gaining strength with stubborn to non-reactive snowpack test results in most areas sampled. 

  While isolated on a regional forecast scale, it’s not impossible that this weak layer and storm slab combination could still be encountered.  It has been found on Northerly aspects, above 8000', in below treeline, or wind protected near treeline terrain.  Even though this storm slab avalanche problem has become unlikely, safe travel protocols and good group decision making still apply.