Salmon River Mountains

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  1.5-2.5 feet of snow earlier this week buried persistent weak layers from our prolonged high-pressure spell. Persistent slab avalanches are becoming isolated and difficult to trigger. You're not likely to receive the same feedback people found during and immediately after the storm (i.e., shooting cracks and whumpfing). You're most likely to trigger a persistent slab avalanche in terrain features similar to those shown in the photo on the right (cool, shaded spots above 6,500 feet that have been harboring weak snow since January). Be heads up around steep, shaded slopes that have been protected from the sun and wind.

  The most sensitive slopes are at mid-elevations near water sources (such as creeks and lakes). These could likely be in small terrain trap features that could catch people off guard. Such as this terrain trap that claimed a life in early January in western Wyoming. Don't let your guard down when there are persistent slab avalanches on the menu. Maintain safe travel practices, like spreading out and keeping eyes on your partners, only expose one person at a time on steep slopes, developing a travel plan for the day, and re-grouping in safe spots away from terrain traps and runouts.

  Persistent slabs are becoming difficult to trigger. The weight of a snowmachine is much more likely to affect buried weak layers than a person's weight. Persistent slabs could propagate widely and be unsurvivable.