Central Sierra Nevada

Problemi valanghivi

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

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

  Probabilità

  Likely

  Dimensione

  2

  Several layers of concern are present in our current snowpack that have developed over the last week.  These buried surface hoar layers exist on NW-N-NE-E-SE aspects in near treeline and below treeline terrain and should be buried anywhere from 4'' to 3' deep.  The incoming, wet and heavy storm will put additional stress and weight on these layers which could make them fail today.  There is high variability and some uncertainty as to where these layers exist throughout the forecast area.  These avalanches have the possibility to propagate large distances, be remotely triggered, and have high consequences. 

  This is a near treeline and below treeline avalanche problem and is not common for our area.  Any slopes that have buried surface hoar will be suspect.  Look for recent avalanche activity, shooting cracks, and whumphing noises.  Use careful terrain selection to avoid steep open areas near and below treeline.  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

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

  Probabilità

  Likely

  Dimensione

  2

  Dense and heavy wind slabs could form today as this winter storm affects our forecast area.  SW wind gusts are expected in excess of 100mph over the Sierra Crest.  Expect wind slabs to form on NW-N-NE-E-SE aspects near treeline and above treeline with the possibility of these winds slabs also forming below treeline in open areas.  With higher snow levels these wind slabs will be much more dense and heavy than the existing snow and could fail near the old snow/new snow interface. 

  Avoid wind loaded areas.  Look for blowing snow, cornice formation, wind pillows and snow surface scouring to help identify where these wind slabs are forming.