Turnagain Pass and Girdwood

Problemi valanghivi

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Possible

  Dimensione

  2–3

  Recent avalanches: Following the widespread natural avalanche cycle last weekend, the most recent human-triggered avalanche occurred on Wednesday, Jan. 21 when a skier remotely triggered an avalanche on the front side of Sunburst, taking out several sets of existing ski tracks.

  There is still a good chance a person will trigger a large avalanche failing on weak, faceted snow buried 2 to 4' deep. This is the same layer that was responsible for the impressive avalanche cycle last weekend, and is still showing clear warning signs. Yesterday, skiers on Fresno and Summit Peak noted significant rolling collapses traveling hundreds of feet — an unmistakable indicator of unstable snow that we don't always see with these persistent weak layers. The layer is buried slightly deeper in Turnagain Pass, but the overall snowpack structure is very similar.

  This setup with a stiff slab on top of a persistent weak layer of facets is not the type of problem we usually deal with. Historically, this type of weak layer has been responsible for the majority of fatalities in our forecast area. We've had a week of warm temperatures without any major loading, but the snowpack is still reactive. While it may be slowly gaining strength, for now it's clearly still a major concern. We continue to see large collapses, poor stability test results, and people triggering large avalanches remotely from low-angle terrain connected to steeper slopes. This behavior is consistent from Girdwood to Seward. This is the kind of scenario that catches people by surprise, and is best managed by avoiding traveling on or below steep terrain. 

  Loose Snow Avalanches: Ice climbers have reported loose snow avalanches initiating in steep, rocky upper elevation start zones and running through gullies. While these have not been big enough to bury a person, they can pose a major threat if they were to pull you off of a climb. They will be most likely on steep solar aspects.