Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Yesterday, wind-blown snow piled up on the downwind sides of ridges, gullies, and wind-exposed slopes. As this wind-drifted snow accumulated, it likely created a more cohesive layer of snow (a wind slab). While today's light NE winds may not move much snow, they could stiffen the wind slabs that formed yesterday. Triggering a wind slab avalanche will remain possible today, especially in windy places near and above treeline. Wind slab avalanches could involve enough snow to bury or injure a person. 

  Clues like wind-drifted snow, cornices above a slope, ripples in the snow surface, scoured areas on the upwind side of a ridge, and other wind-created surface features can help determine where wind-blown snow has piled up. Recent avalanche activity and cracking in wind-blown snow represent clear signs that the wind slabs remain unstable. Identify where wind slabs may exist and plan routes around the wind-loaded areas. Sheltered terrain can help reduce your exposure to wind slabs and increase your exposure to soft, non-wind-affected snow.  

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–1.5

  Cooling temperatures during the storm produced snow that got lighter as it piled up. The colder temperatures may also slow down the new snow's ability to bond to itself. Yesterday, it was easy to trigger sluffs of loose, dry snow on steep slopes, and those may remain possible today.  Most of these should remain small, but they might still be problematic around trees, rocks, cliffs, or other terrain traps that magnify the consequences of an avalanche.