Salt River and Wyoming Ranges

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1.5–2.5

  We continue to see bulls-eye evidence of this problem in the form of avalanches as well as cracking and collapsing. The layer of weak sugar snow left over from the cold and dry November sits under a slab that could be 2-3’ thick. Steep, rocky northerly terrain will be the easiest location to find this problem but it is more widespread at upper elevations and wherever facets exist at the bottom of the snowpack. Multipleobservations over the last week have shown this problem to be reactive with riders continuing to see evidence of instability. In some areas of the zone we have an ice crust buried under the slab. Although this crust feels hard as you travel, do not be fooled into thinking it isolates the top slab from the weak, sugary snow below. We have seen failure and slab propagation below this crusts in avalanche observations and snow pits.

  Continue to travel on slopes less than 30 degrees that are not connected to steeper slopes above.  Take the time to investigate what’s beneath you. Watch for shooting cracks and listen for collapsing. Dig a hand pit, probe, or look at what your snowmachine has trenched through. If you find sugary snow you have found the weak layer. Hard slab avalanches can be unpredictable, fail remotely from below or above and propagate farther than you might expect. This observation from the Tetons yesterday is a scary example of how far away an avalanche can be remotely triggered. Tracks on a slope do not mean it is safe - it only means that those tracks did not find the location of the trigger point. The next tracks could! Keep an eye out for terrain traps as you travel and remember that even a small slope above a trap can bury you quickly.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  1–2

  The wind slab problem is trending down, and it is unlikely you will trigger a wind slab avalanche. Snow and wind from the weekend  formed wind slabs on lee terrain along ridges and exposed terrain above 9500’. These slabs are around 1-2' thick and are sitting on top of an already weak snowpack with poor structure (slab over weak sugar snow), adding weight to the persistent slab problem. Remember that even a small wind slab avalanche can step down and trigger the deeper instability in our current snowpack. 

  As you travel, feel for denser snow in these locations and look for pillows. These are sure signs of wind-distributed snow. Watch for cracking and collapsing in this snow. This problem can also be found below ridges and around terrain features that have been cross-loaded by the wind.  Seek out sheltered and low angle terrain.