Galena Summit & Eastern Mtns

Problemas de aludes

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Likely

  Tamaño

  2–3

  There are two persistent weak layers of concern in our snowpack:

  1. A thin layer of facets and sporadic surface hoar buried 1.5-2' deep. This layer formed during a week of cold, dry weather, and was quickly loaded by the late-January snowpocalypse. It appears to be responsible for a large portion of the avalanche activity over the past week. Observations indicate that it is becoming less problematic in the western side of this zone (Smokys and Galena Summit area), but remains a concern in the eastern portion (Pioneers and Boulders). 
  2. Our well-known layer of December facets buried 3' deep or more. In contrast to our newer weak layer, this layer formed over a long period (3+ weeks) and was very slowly loaded. Now that it's deeply buried, it's behaving more like a deep slab problem. In other words, difficult to trigger with terrible consequences if you do.

  We are in the midst of a multi-day wind event that is producing strong W to NW winds. These winds are loading many slopes at middle and upper elevations, keeping these weak layers on edge. Avoiding slopes over 35 degrees and/or those that have been affected by the wind will greatly reduce your chances of triggering a persistent slab avalanche.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta montaña
  • Límite del bosque
  • Bajo el límite del bosque

  Probabilidad

  Likely

  Tamaño

  1–2

  Welcome to day 3 of our ongoing NW wind event. Yesterday, observers again reported large quantities of snow getting transported. I was above Prairie Creek and watched the wind rapidly loading a SE-facing slope. Further up the ridge, I remotely triggered a small(ish) wind slab avalanche on this same slope from about 50 feet away. Check out the video (above/right)—it provides an excellent example of how a slope loads, wind slab surface clues, and the end result. In some areas, the wind is running out of "ammo" as windward slopes become devoid of transportable snow. But some portions of this zone received an inch or two of new snow, and this can quickly turn into a foot or more of fresh wind slab.

  Wind slabs will be most common and dangerous along upper elevation ridgelines and in alpine terrain, and can be easily identified by surface texture and by their pillowed, rippled, or dune-like appearance. From an avalanche danger perspective, the larger concern is still the additional loading on the persistent weak layers described above. If a wind-loaded slope fails on one of these layers, the resulting avalanche will be much larger.