Granny Classic Crater Lake

Skiing the Granny Classic at crater lake, a group of three skiers triggered a 2.5-3 size storm/wind slab avalanche with a crown of approximately 60m wide and 0.8-1.10m depth that ran for approximately 350-450m.. A windy day with moderate visibility, we chose to ski the guts of Granny Classic. Cornices in the area were more pronounced than in previous years and there were many exposed rock features that would normally be covered. As a group of three, we decided to ski one at a time, posting up in areas of relative safety before calling down the next skier. The second skier in the group triggered the slide and made two lovely turns before a shoulder check revelealed a large avalanche overhead and gaining speed. The first skier in the group was able to fairly easily secure a safe position and the slide deflected around them off the rock outcropings. The remainder of the run was uneventful and we took the same accordion approach moving from one island of "safety" to the next. A few notes 1). When discussing our line, our biggest concern based on what we could see were core shots, which i still managed afterwards, and not avalanches. The wumpfing noted was much lower on the approach, where you leave the Prairie and start climbing again. There was no whumpfing or shooting cracks prior to the release. 2) As the second skier who triggered the slide, i would have had no idea it had even happened if i hadn't shoulder checked, which I'm notoriously bad for forgetting to do. It seems the release point was about a foot DOWNHILL of my turn and i didn't even see it. I managed 2 very nice turns underneath the release point before shoulder checking, seeing the slide and skiing out of it's path. 3) both the first and second skier yelled AVALANCHE when noted. The third skier, who was posted up in a safe zone, heard the second skier but not the first. The second skier did not hear the first. The third skier did not see the avalanche due to a convexity we were being mindful of and his first clue to trouble was the shout from the second skier.. 4) the crown of this slide was large, varying from at least 80cm to perhaps as much as 110cm or more in places. Frankly, i was surprised how far across the run it propogated, covering nearly the whole of the Crater Lake Classic runs. We all had avi training and all had the requisite safety gear as well as comms. We made the best decisions we could with the information we had at the time, openly discussed our thoughts and concerns and ultimately we managed to avoid calamity. Of note to me here was that as big a slide as this was, it did NOT appear to step down to the weak layer we've all been managing this year. This implies a surprising amount of wind deposited snow. You'll have to forgive me for not sticking around too long to properly assess the slide surface but in my defense there was some concern about hang fire as the trigger point was pretty downhill of the roll. All in all, a good day as we all skied away from it. Having a plan and skiing the plan really worked out for us here. Have fun out there everyone and be super safe enough!