Galena Summit & Eastern Mtns

Avalanche problems

• 

  Wet Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2.5

  Two varieties of wet snow avalanches are likely on steep, wind-sheltered slopes. Large Wet Slab avalanches may release naturally as buried persistent weak layers become wet. Smaller Wet Loose snow avalanches are very likely to be triggered and could entrain large amounts of snow as they move downhill.

  1. Wet Slab avalanches are unpredictable, can break widely, and occur without obvious warning signs. These avalanches are expected to break 1-4 ft deep on lubricated buried crusts or wetted weaker snow layers underneath slabs formed in February and March.
  2. Wet Loose avalanches are more predictable and typically start as small point releases before entraining snow and fanning out below. These slides often initiate near the base of trees, rocks, and cliffs, and primarily will involve only the recent snow. These slides can trigger larger slab avalanches (example) as they move downhill.

  Rollerballs (video), pinwheels, and wet, slushy snow surfaces are clear signs the snow is heating up and that wet avalanches may follow. Even small wet slides are surprisingly difficult to escape and are consequential above terrain traps such as gullies, creeks, and trees. Minimize your time spent under steep, sunny slopes, especially those with rock and cliff features that warm quickly, and particularly later in the day.

  Additional Discussion - Cornices: Cornices could break on their own as they sag during the multi-day heat spell. Natural cornice fall can trigger both wet loose slides and larger slab avalanches.

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1.5–2

  It is possible to trigger a 1-3 ft thick persistent slab avalanche on buried weak layers (sugary facets, surface hoar, and crust + facet combinations) on slopes where the snowpack remains cold. This problem is worst on wind-loaded, middle and upper elevation terrain facing NW-N-NE-E.  The last storm formed wind slabs below corniced and exposed ridgelines, on the sides of cross-loaded gullies, and in cirques below steep faces, large cliff bands, and chutes.

  Look for smooth snow pillows, dunes, textured snow surfaces, and cornices as indicators of wind-stiffened snow. Snowpack cracking and collapsing are clear signs of unstable conditions. However, don't expect to experience obvious signs of instability; the first clue may be the avalanche you trigger. Avalanches could break above you and wider than expected. Avoiding avalanche terrain is the only surefire way to manage this problem.