Soldier & Wood River Valley Mtns

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2

  You could trigger 1-3 foot thick slabs in wind-loaded terrain. Natural avalanches are possible, and cornices could fail and trigger slabs on the slopes below.  Avalanches could be wider than you expect, and very easy to trigger, due to persistent weak layers (facets and crust + facet combinations) buried below the slabs on many slopes that face the northern half of the compass. You may be able to remotely trigger avalanches from lower-angled terrain above, below, or to the side of a steep slope.

  Expect to find slabs near and below ridgelines, on the sides of cross-loaded gullies, and on aprons beneath chutes. The wind slabs will be most widespread at upper elevations but will also exist in middle and lower elevation terrain. 

  Wind-drifted snow will feel stiff and may keep you on the surface. Watch for dunes, drifts, and snow pillows. Cracks shooting out from your skis or boards are a clear sign you've found a wind slab. 

  The size and chance of avalanches will increase as the day progresses. The slope you safely played on in the morning may not be safe later today. You can reduce your risk by steering clear of large, wind-exposed avalanche paths, including the runouts where avalanche debris would end up. 

   

  

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  In areas more sheltered from the wind, the chance of slab and loose snow avalanches will increase as the storm progresses. These avalanches are most likely on slopes steeper than about 35 degrees where more than a foot of snow has fallen.

  The storm snow sits atop facets,  facet + crust combinations, and crusts, depending on aspect and elevation. Slabs and sluffs will be easier to trigger in some areas than others, and the differences in stability between aspects may not be easy to recognize. 

  A kiss of wind, mild temperatures, or a little drizzle or rain is all it takes to consolidate the storm snow into a touchy slab. Although smaller than the thicker wind slabs described above, this problem could be tricky to manage. Slabs may release in surprising ways and break wider than expected. They may be triggered from a distance—above, below, or to the sides of steep slopes. It will be hard to predict which slopes are becoming unstable as the storm progresses, so build a wide safety margin to handle the uncertainty. 

  Expect heavy sluffing on many steep slopes. Triggered slides of any form may quickly gain mass and speed as they move downslope on hard crusts.