Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Intense blowing snow with gale force NE winds continue into this morning after an impressive 24 hour plus period of sustained winds.  These NE winds should start to decrease this morning and shift to the SW sometime this afternoon.  SW winds will pick up in speed this afternoon/evening and could start to transport snow.  Wind slabs could exist on any aspect in near and above treeline areas.  Extensive wind scouring will exist in most wind exposed terrain and even in some below treeline terrain.  A patchwork of wind slab and firm scoured surfaces will exist with some of these wind slabs having hard slab characteristics.

  Travel conditions will have deteriorated in wind exposed areas in near and above treeline terrain.  Look for continued blowing snow, new cornice formation, wind pillows, and snow surface clues to identify where unstable wind slabs may exist.  Use caution around steep wind loaded terrain and cornices.  Wind protected below treeline terrain will continue to hold the best chances for soft snow.  

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Sunny skies and warming temperatures will allow a loose wet avalanche problem to develop as daytime warming occurs.  This problem will be very dependent on how much cloud cover builds into the afternoon and how fast the NE winds decrease this morning.  Areas that receive full sun into the midday in wind protected locations will have increased chances for loose wet instabilities to form.  Roller balls and pinwheels are expected to occur within the recent storm snow on all aspects.  Larger loose wet avalanches could become possible and involve more snow if rapid warming continues through the day.  

  Once the snow surface becomes wet and deep, its time to change aspects or move to lower angle terrain.  Terrain traps and downhill hazards could increase the consequences of being caught in a small loose wet avalanche.