Togwotee Pass

Avalanche problems

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–1.5

  The threat of natural and human-triggered wet loose avalanches will increase through the day with clear skies and above freezing temperatures. As temperatures warm, snow surfaces may destabilize, causing avalanches on solar aspects up to 10,500' The largest of these will occur on very steep, rocky slopes directly facing the sun, where solar input is greatest. This problem will follow the sun, starting with east aspects and wrapping around to south, then west aspects as the sun moves across the sky. These avalanches often initiate as a 'point release' near exposed rocks, the base of trees, or at your feet, and grow in size as they travel downhill entraining snow. Watch for early indications of a warming snow surface such as rollerballs, pinwheels, or wet surface snow. Even a small wet loose avalanche can quickly knock you off your feet and drag you downhill.  Give yourself options, including low-angled routes and exits not threatened by steep sunny slopes above. Seek cooler, shaded terrain if you find snow becoming wet and unstable. 

  Additional Discussion: Large cornices may be found on upper elevation ridgelines.  As temperatures warm, cornices will weaken, and could release naturally. Limit time beneath these features and remember that cornices can break further back than expected on ridgelines.

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1.5–2.5

  Slabs overlying weak layers buried 2-3 feet deep remain possible to trigger on very steep slopes over 35°. Warming temperatures throughout the day will increase the sensitivity of slabs overlying weak layers and increase the likelihood of avalanches during peak hours of warming. Signs of instability such as cracking, collapsing, or recent avalanches may not be present before triggering a large, dangerous avalanche capable of propagating far across or upslope. Multiple tracks on a slope do not indicate that a slope is stable. Stick to lower consequence terrain away from terrain traps and rocky, convex, very steep slopes today.

  

• 

  Deep Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  2–3

  Weak snow buried 5 feet deep exists near the ground above 9,000’. Triggering an avalanche at this depth is very unlikely but not impossible.

  On February 10th, a rider stepped off their sled and triggered a very large avalanche that failed near the ground on Lava Mountain. This avalanche was triggered where the overlying slab was thin making it possible for the rider to impact the underlying weak layer. Manage this problem the same way you would manage weak layers in the middle of the snowpack by avoiding very steep, rocky, and wind loaded terrain.