Summit Lake

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1.5–2.5

  Recent Avalanches: New glide avalanches continue to be observed daily in Girdwood, Turnagain Pass, Summit Lake, and Seward. Glide avalanches aside, the last known avalanche activity in the Summit Lake zone was almost two weeks ago, when two separate groups triggered large avalanches remotely on Tenderfoot Ridge.

  The multiple weak layers of buried surface hoar in the upper 3' of the snowpack remain the main concern for now. These layers are slowly gaining strength, but it is really hard to say just how reactive they remain. Although they are trending in the right direction, we're still concerned that somebody will trigger a large avalanche on one of these weak layers. Here are a few things to keep in mind as you travel:

  • These layers give unreliable feedback, often lacking any warning signs even when conditions are dangerous.
  • These layers are slow to heal, and often catch people by surpise days or weeks after they are buried.
  • As of now, the most likely place to run into trouble will be at upper elevations where there is no crust on the surface. In other words, exactly where the best surface conditions exist.

  You can minimize your exposure to a problem like this by choosing simple terrain with lower slope angles and no consequential features like gullies, cliffs, or trees in the runout zone. We're heading in the right direction with the stability trend, but this is still a problem that should be treated with caution.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1.5–2.5

  The wind that arrived yesterday afternoon likely built fresh and reactive wind slabs, especially at upper elevations. These will be around a foot deep or deeper, and they will still be reactive today. Be on the lookout for this problem in steep terrain just below ridgelines, convex rolls, and in steep gullies. If you notice a transition from softer snow to punchy, stiffer snow on the surface as you travel, you have likely found a wind-loaded slope. There is a chance that even a smaller wind slab triggered at the surface could step down to make a bigger avalanche failing deeper in the snowpack, described in Problem 1 above.

• 

  Glide Cracks

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  2–3

  The ongoing glide avalanche cycle remains a major concern throughout our forecast zones. These avalanches are destructive and impossible to predict. We often see these avalanches continue to release, or even release more frequently, during cold snaps like we are currently experiencing. One thing that makes this cycle particularly noteworthy is that we are seeing avalanches release on slopes without any prior glide cracks. This is a tricky problem, and the best way to manage it is by limiting spending any time in runout zones below steeper slopes, and by traveling one at a time through avalanche terrain.