Central Sierra Nevada

Problemi valanghivi

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  1

  Some wind slabs may still linger on near treeline and above treeline NW-N-NE-E-SE aspects. In most cases, triggering one of these wind slabs should have become more difficult. However, some human-triggered wind slab avalanches may remain possible especially in cliffy areas, unsupported slopes, couloirs, and other complex or extreme terrain. Some of the cornices hanging above the slopes may also remain fragile.

  Identify wind-loaded terrain features using clues like drifted snow, cornices above a slope, hollow-sounding firm snow, and other wind-created surface textures. This information can help manage the conditions and terrain to maintain appropriate safety margins around lingering wind slabs. 

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Unlikely

  Dimensione

  2

  As the storm snow and the older weak snow below it have gained strength, triggering a persistent slab has become unlikely. The weak layer remains (facets buried in the snowpack), but data seems to indicate that it has adjusted to the load above it in many places. Also, getting enough force through the strong storm snow layers to break this layer would be difficult. Still, this problem may not be impossible in an isolated area where conditions are just right.

  Even though persistent slabs are unlikely, paying attention to whether or not this layer exists is a good plan. Use probing and snowpits to find and identify this layer. Areas where it is closer to the surface or where trigger points exist may represent some of those isolated areas where a surprise might still happen.