Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1

  New snow along with moderate to strong S/SW winds will form new wind slabs on W-NW-N-NE-E-SE aspects in near and above treeline terrain.  Wind slabs and cornices will build throughout today and be reactive to natural and human triggering.  Warming temperatures with potential rain on snow this afternoon could further weaken these wind slabs. 

  Look for blowing snow, cornice formation, and wind pillows.  Avoid steep wind loaded terrain and areas below large cornices.

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1

  Storm slabs could form on all aspects in wind protected near and below treeline terrain.  Weaknesses could develop within the new storm snow or at the old snow/new snow interface.  With snow levels forecasted to rise throughout the day, upside down storm snow conditions could occur with heavier snow on top of less dense snow.  Where rain on new snow occurs, storm slab avalanches could take on wet slab characteristics.

  Look for cracking or any indication of cohesion of the new storm snow.  Rain on new snow could cause widespread instabilities.  Match appropriate terrain for the current conditions.  

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1

  Loose wet avalanches will become likely in areas that receive rapid warming with rain on snow.  As snow levels rise throughout the day, potentially up to 7500', loose wet avalanches could entrain most or all of the new storm snow.  Some of these loose wet avalanches could be large enough to injure or bury a backcountry user.