Sawtooth & Western Smoky Mtns

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  1.5–2.5

  While unlikely, we can't write off triggering large avalanches in middle and upper elevation terrain. Unfortunately, you may not receive any obvious signs of instability before triggering one of these lingering monsters. There are two sets of weak interfaces to be aware of:

  1. Deeply buried weak facets — Found near the ground on middle and upper elevation slopes, especially those facing away from the sun. Triggering a slide on this layer is most likely in windy and/or rocky areas where the snowpack depth is variable and in more sheltered terrain where the snowpack is around 3 feet deep.
  2. Rain crusts or crust + facet combinations — Found in the upper half of the snowpack on most middle elevation slopes. Evidence suggests that these are healing, but their high variability with elevation and aspect makes their behavior hard to predict.

  You can reduce the chances of triggering these avalanches by avoiding steep, wind-affected, or rocky slopes.

  Additional Discussion: You may be able to trigger wind slab avalanches that formed near ridgelines and in cross-loaded areas on the sides of gullies.  Look for recent cornice growth, dunes, or ripples in the snow surface. These are signs the wind has been at work, transporting snow.