Central Sierra Nevada

Problèmes avalancheux

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  The vast majority of our snowfall events are accompanied by SW wind. This storm has been different, with a constant NE wind. As a result, expect the distribution of wind slabs to be different from a typical day with new snow. The substantial bias in snowfall amounts from one portion of the forecast area to another will also make this avalanche problem present in some locations within the forecast area and completely absent in others.

  NE winds have blown and drifted new snow overnight, filling in places on the leeward sides of ridges, in gullies, and on open slopes. This is expected to have created cohesive slabs of locally deeper wind-deposited snow. These new wind slabs may have formed on top of either sugary faceted snow at the old snow surface or on top of firm ice.

  Look for blowing snow. Identify where it has drifted and filled in, making locally deeper areas of new snow within the terrain. These are the locations of concern for a wind slab avalanche. Recent avalanches and cracking in the snow surface are clear signs that new wind slabs are unstable. Traveling in wind protected areas such as tree-covered slopes or places where other terrain blocks the wind can reduce exposure to this avalanche problem.

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Unlikely

  Taille

  1–1.5

  Some small dry loose sluffs may be triggered today by backcountry travelers in steep terrain. Anticipate this avalanche problem on any aspect in locations where at least a couple of inches of new snow has accumulated. These small dry loose avalanches could run on exposed rain crust, on top of soft faceted snow at the old/new snow interface, or within the new snow. For today, most of the hazard associated with this problem comes from being carried into or over down slope hazards such as rocks, trees, or cliffs rather than from burial.

  Selecting less steep terrain can be an easy way to avoid this avalanche problem. Otherwise, if opting for steep terrain, choose sections of terrain that avoid consequential down slope hazards.