Central Sierra Nevada

Problemas de aludes

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Very Likely

  Tamaño

  2

  Wind slabs will exist on wind-loaded N-NE-E aspects and on cross-loaded NW and SE aspects. The largest wind slabs should exist in near and above treeline terrain but some could also lurk in exposed below treeline areas. Human-triggered wind slabs will be likely today and natural wind slabs are possible. Wind slab avalanches could be large and destructive. In areas where wind slabs may rest on buried surface hoar, remote triggering is possible and avalanches could propagate wider than normal or even across connected slopes. As snow accumulation and winds increase this afternoon/evening, wind slabs will quickly grow in size and become more widespread. Widespread natural wind slab avalanches will become likely this afternoon and during the night.

  Blowing snow, cornices above a slope, drifted snow, and other wind-created textures can help identify where wind slabs may exist. Giving these areas a wide berth would be a prudent plan for today. Sheltered low angle slopes without overhead hazard could provide better and safer recreation opportunities.

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Very Likely

  Tamaño

  1

  Storm slab avalanches large enough to bury a person are likely today. Some may involve even more snow. Changing conditions during the storm will have created weaknesses within the storm snow including some heavier snow on top of lighter snow. In addition to this upside-down layering, the new snow rests on top of a layer of weak feathery snow (surface hoar) in many areas. Storm slab problems could exist on any slopes steep enough to avalanche. Storm slabs could fracture wider than expected or be remotely triggered. They will become more widespread and larger with the arrival of the next storm. Natural storm slabs will become likely this afternoon and tonight.

  Cracking and collapsing can indicate that storm snow weaknesses or buried surface hoar exist. Today's complex and dangerous avalanche conditions warrant conservative decisions and route choices. Sticking to lower angle terrain without overhead hazard could be one way to create appropriate safety margins. 

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Likely

  Tamaño

  3

  The new snow has added a significant new load to the snowpack making deep persistent slab avalanches possible. The persistent weak layer now exists more than 3 to 5 ft below the snow surface. Smaller triggers in the right places like a person on a trigger point or larger triggers like cornice collapses or other avalanches could cause a deep slab to release. If a deep slab avalanche does occur, it would likely be large, destructive, and unsurvivable.  The additional snow load expected in the next storm may make deep slab avalanches more likely.    

  The consequences of a large destructive deep slab avalanche are high. Unfortunately, these are hard to predict and the first sign that a deep slab avalanche may occur could be a deep slab avalanche. Avoiding steep terrain where this weak layer may exist represents one of the only ways to effectively deal with deep slab problems.