Central Sierra Nevada

Problèmes avalancheux

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Unstable wet snow will become possible on all aspects as snow levels rise today. Rain may fall on new snow that accumulated during the onset of precipitation this morning or on old snow. Either way, wet loose snow could slide downhill, gathering more wet snow as it moves. Wet snow instabilities will be most prevalent below the rain line but could extend slightly higher into areas where heavy wet snow falls instead of rain. In some cases, the heavy, wet snow/rain could cause the old, weak surface snow below it to break, resulting in small slab avalanches of wet or storm snow. The protected northerly aspects where soft snow has lingered during the dry spell hold the best potential for these. 

  Rain on snow, roller balls, and pinwheels indicate that wet avalanches are possible. Cracking and recent avalanches provide great clues that those hybrid wet/storm slabs mentioned above could occur. Many of these may remain small, but some could entrain enough wet snow to bury or injure a person as more precipitation falls or in areas where more old soft snow existed before this storm. 

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Wind-blown snow will fill in areas on the downwind side of ridges, gullies, and open slopes with slabs of locally deeper snow as new snow and strong winds impact the forecast area today. These wind slabs may not bond well to the old snow surfaces below them. Wind slab avalanches will become possible today. These will start small and limited in distribution this morning, but they could grow larger as more snow accumulates later this afternoon and evening. They could also become more unstable as they grow since the snow will get heavier as the storm progresses.

  Conditions will change quickly as this storm impacts the region. The same slope may go from only having a small amount of wind-blown snow in the morning to holding a wind slab large enough to bury a person while you have lunch. Blowing snow provides a great clue that wind slabs are building, and recent avalanches or cracking in the wind-blown snow represent clear signs that they are unstable. Identify where the blowing snow has drifted and filled in, making locally deeper areas of new snow. These places will hold the potential for a wind slab avalanche. 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.