Sawtooth & Western Smoky Mtns

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Very Likely

  Size

  2–3

  The weight of recent storm snow is pushing buried weak layers to their breaking point. Natural avalanches are likely today in areas where the wind builds thick drifts. Human-triggered avalanches are very likely and may even occur in areas that are mostly sheltered from the wind. You're most likely to trigger a persistent slab avalanche on steep slopes that tilt away from the afternoon sun (NW-N-NE-E). It's these aspects that produced the most widespread natural and human-triggered avalanches over the last two weeks, and where our buried weak layers remain the most concerning. 

  Triggered avalanches may be 2-5' thick and release in surprising ways. They can be much wider than expected and be triggered remotely—from flat terrain below, above, and to the sides of steep slopes.  

  Snowpack cracking and collapsing are clear signs of unstable conditions. The best way to avoid trouble is to give avalanche terrain a wide berth. This includes gentler terrain below steep slopes or under large avalanche paths. 

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Very Likely

  Size

  2

  Up to 2 feet of snow and driving wind have built 2-4' thick drifts and slabs at upper elevations. Expect these drifts to be the largest and most sensitive on slopes facing NW-N-NE-E. 

  Look for them near or below ridgelines, along mid-slope ribs, and on aprons beneath chutes. Rapid cornice growth, dunes, or drifts are all signs that the wind has been at work. 

  Today's intense wind-loading will likely cause wind slabs to release naturally. Even if you're in an area sheltered from the wind, it's prudent to avoid the runout of large avalanche paths. These smaller wind slabs may trigger the larger persistent slab avalanches described above.