Rock N' Roll 2.5

Had a good day turn bad around Cayoosh today. Party of three skied up the normal ascent route for Cayoosh and observed some recent slides on S aspects close to ridgeline and surmised that these were likely windslabs following the strong winds that were noted this week in the Duffey. We dug a pit on NE aspect at the top of Cayoosh glacier and got minimal results on a CT and ECT, found the new storm snow bonding well to the snow below and decided to go ahead with our objective of Million Dollar Couloir, which skied great without incident. We decided to then do a lap from the Rock N' Roll ridge line, figuring we could stick to low-angle treed terrain along the shoulder skiers right of the Rock N' Roll gulley feature before dipping into the gulley low to avoid wind slabs that we felt were likely around ridge top. We were unfamiliar with this feature and got sucked closer than we expected to the gulley as we descended. About halfway down, the first skier in our group dropped in from a safe zone. Just as the second skier dropped, a slide propagated uphill of the second skier, catching both skiers who slid all the way to the bottom of the Rock N' Roll gulley. The third skier was not caught. The first skier miraculously ended up on top of the debris with no injuries. Second skier was fully buried and the third skier located and extracted them within approximately 5 minutes of the slide. The buried skier was injured and airlifted out. Crown was about 75cm thick and propagated about 60-80m, with lots more snow getting pulled in from the sides of the gulley. My belief is the recent storm snow failed on a sun crust. Perhaps it was a wind slab but it skied more like storm snow and was lower than the elevation we expected to see windslabs. Thanks to Pemberton SAR and the other skier group that came to our aid today.