Central Sierra Nevada

Problèmes avalancheux

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1

  A wind slab avalanche problem will form quickly this afternoon following the onset of snowfall. The vast majority of wind slabs will form near treeline and above treeline on NW-N-NE-E-SE aspects and to a lesser extent in other locations including wind affected areas below treeline. Identify and travel around the edges of areas where wind drifted snow is depositing in avalanche terrain, especially near cornice features and wind pillows.

  In Sierra Crest locations where weak snow and thin crusts have been observed within the top 4 to 18 inches of the existing snowpack, additional travel considerations will become warranted as this storm cycle progresses. The collapse of these weak layers below the old snow surface may allow for wind slab avalanches to take on some persistent slab characteristics, failing wider than typical, possibly wrapping around corners and across adjacent avalanche paths all at once. As these areas of higher uncertainty develop, give wind slabs a wider margin of safety than normal.

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Likely

  Taille

  1

  A storm slab avalanche problem may form this evening and during the overnight hours as snowfall rates of 1-2" per hour create for rapid accumulation in wind protected areas. Storm slabs could form on any previously snow covered slope in below treeline or near treeline terrain.

  In areas where snow surface cracking occurs while making fresh tracks either uphill or down, identify and move around the edges of avalanche terrain.