Gunnison

Lawinenprobleme

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  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–1.5

  The recent snow accumulations at the end of the week averaged around 2 to 6". This snow has been transported by southwest to northwest winds aloft and created small wind slabs near ridgelines and cross-loaded terrain features. This avalanche problem doesn't appear to be widespread across suspect terrain, as the low-density snow was simply blown away in some areas. The most sensitive drifts are expected to be encountered on the eastern half of the compass. Fresh cornice formation and adjacent scouring are useful clues to identify suspect leeward terrain features. Cracking, collapsing, and stiffer feeling snow are clear signs you have found the problem.

  

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  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–2

  During the week of February 7th, several wind events lead to incremental wind loading and a resulting stack of thin hard slabs. These slabs were the most problematic at near treeline elevations on the eastern half of the compass and were more isolated in their distribution at other elevations. At the end of that week, multiple backcountry riders were caught and carried by these hard slabs breaking into faceted layers of old snow. 

  This avalanche problem can no longer be identified from snow surface clues. Probing and feeling for hard slabs over thin layers of weak snow is one strategy, but by the time you find the avalanche problem, you will be on the avalanche problem. The best travel advice is to manage the terrain for a wind slab avalanche problem. As these hard slabs formed on the lee sides of tree fences, on the lee sides of ridged terrain features, and in concave catchments such as gullies.

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  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Hochgebirge
  • Waldgrenze
  • Unterhalb der Waldgrenze

  Wahrscheinlichkeit

  Possible

  Größe

  1–1.5

  Dry loose avalanches (sluffs) are a concern in wind-sheltered terrain on the north half of the compass.  Where the snow surface is weak and cohesionless, you can easily trigger sluffs that entrain the top 8" to 14" of loose snow on slopes steeper than 35 degrees.  The recent storm has increased the snow available for loose avalanches to entrain.  Ski cuts, moving across the fall-line while descending, or choosing lower-angled slopes are effective techniques to manage this problem. These point-release avalanches will accumulate more mass in long-running, steep terrain. Use caution above gullies where an avalanche can pile more deeply and above trees and cliffs where the consequences of getting caught in a sluff will be magnified. This problem is most common in sheltered terrain below treeline, but you can also trigger sluffs on some near treeline slopes and a few above treeline slopes.