Turnagain Pass and Girdwood

Problèmes avalancheux

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  2–3

  We are still concerned that a human could trigger a large avalanche on a layer of surface hoar buried 2 to 3’ deep. This type of weak layer can take a long time to heal and has been responsible for over 20 human triggered avalanches. People have triggered avalanches above them from relatively flat terrain. Human-triggered avalanches on this weak layer have occurred on slopes with many tracks on them so do not assume these slopes are safe.

  This is a challenging situation as the snow is transitioning into a spring snowpack. There is a stout crust on the surface of the snow which usually makes people feel safer but as this crust heats up and melts it will dramatically increase the chance of triggering a large avalanche. Places where the crust does not exist and the snow is dry like in upper elevations and on north slopes it will be easier to trigger an avalanche. 

  The safest option is to avoid traveling on or below steep slopes. If you choose to travel in steeper terrain avoid slopes with gullies or creeks at the bottom of them. These are terrain traps where snow can pile up and make rescues very difficult. Other places that could have higher consequences are slopes with trees and cliffs. Most human triggered avalanches on this weak layer have been on Seattle Ridge and in Lynx Creek areas. That being said we are still seeing the same scary setup on the skier side of the road (Cornbiscuit observation). 

  

• 

  Glide Cracks

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  2–3

  As we transition into spring conditions, slopes exposed to the sun (east, south, west) become more dangerous as they heat up. It is smart to move to low angle terrain or to shadier slopes when you start sinking into wet snow. These sunny slopes are where we are seeing more glide avalanches, wet loose avalanches, and cornices falling and triggering avalanches. 

  We are in the middle of a glide avalanche cycle where many glide avalanches are releasing on east, south and west slopes. Yesterday a glide avalanche released above and to the south of the snowmachine uptrack on Seattle Ridge. These have the potential to run to valley bottoms. The safest option is to avoid spending time under glide cracks or even steep overhead slopes as they heat up in the afternoon. 

  Wet loose avalanches have been releasing naturally and will be easy to trigger on sunny slopes (east, south, west). These may become large enough to carry a person off of a cliff or into a terrain trap. A wet loose avalanche could trigger a larger avalanche on a buried weak layer. 

  Cornices have been falling across the region and triggering large avalanches on slopes exposed to the sun. Try to avoid spending time underneath cornices if you are on sunny slopes and it is wise to stay away from them on ridgelines.

  

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpin
  • Limite forestière
  • Sous la limite forestière

  Probabilité

  Possible

  Taille

  1–2

  Moderate winds overnight and today will continue to create fresh wind slabs around a foot deep or deeper in upper elevations. Look out for blowing snow that will be actively loading slopes and creating touchy wind slabs. In some places they may be forming over a slick crust which will make them easier to be triggered. 

  Traveling on snow that becomes stiff and hollow sounding as well as seeing shooting cracks underneath you are all clues that you are traveling on wind slab. Slopes may appear soft and pillowy or may not appear to have a crust on them which are also indicators a fresh wind slab has formed over a crust. These will likely exist below ridgelines and on convex rollovers.