Galena Summit & Eastern Mtns

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1.5–2

  What and where is it? While not likely, you could trigger a 1-3 ft thick persistent slab avalanche on buried weak layers (sugary facets, surface hoar, and crust + facet combinations). This problem is worst on recently wind-loaded, middle and upper elevation slopes facing NW-N-NE-E. However, today's rapidly warming temperatures and muted sunshine make recently wind-loaded avalanche paths facing the southern half of the compass suspect.  

  How do we recognize and manage it? Avoiding avalanche terrain is the only surefire way to manage this problem. Short of that, you can reduce your risk by avoiding large, obviously wind-loaded avalanche paths and those with ugly consequences if you are caught in a slide.

  • Look for dunes, textured snow surfaces, and cornices. 
  • Feel for changing surface conditions. Wind-affected snow is stiffer than the powder found in sheltered locations. Wind-loaded areas may feel or sound hollow or "drummy."

  Snowpack cracking and collapsing are clear signs of unstable conditions. However, don't expect to experience obvious signs of instability; the first sign you see could be the avalanche you trigger. Avalanches could break above you and be wider than expected. 

  Additional Discussion - Wind Slabs: Observers reported fresh natural avalanches in wind-loaded terrain in the White Cloud Mtns, and several large avalanches released naturally in the western Smoky Mtns near the end of the recent storm. In recent days, snowfall and strong, gusty wind formed wind slabs up to 2 feet thick below corniced and exposed ridgelines, on the sides of cross-loaded gullies, and in cirques below steep faces and large cliff bands. Wind slabs are larger and more widespread in the northern and western parts of this zone where more snow fell.  You may find wind slabs lower on slopes than you'd expect. Give cornices a wide berth; they can break on their own or with the weight of you or your sled. Falling cornices are great triggers for wind slab avalanches.

   

  

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  What and where is it?  Steamy, sauna-like conditions and periods of sunshine could produce natural wet loose avalanches. The majority of these slides should be relatively small, involving the recent snowfall and wind-blown snow. You're most likely to trigger or see wet loose avalanches on very steep, wind-protected slopes where more than about 6" of snow fell during the last storm. 

  How do we recognize and manage it? Sun and heat can rapidly produce loose snow avalanche instabilities. Watch for rollerballs or pinwheels moving downslope, signs the surface snow is moist. Move to cooler slopes or gentler terrain if the surface snow gets wet and mushy. Loose snow avalanches begin as a point, entrain snow as they move downhill, and are surprisingly difficult to escape. Fresh cornices could break on their own, producing loose snow avalanches on steep slopes under them.  Don't linger on or below large avalanche paths with damp or moist surface conditions, especially slopes guarded by large cornices.