Please read the account of an incident that occurred up Crystal Creek in the Middle Fork about 3 PM on Thursday. Thankfully, nobody was hurt and Mike and his group were willing to share their story. We are initially classifying the avalanche as a SS-AS-R2/D2-O (Soft Slab- Skier Triggered- Small relative to path/Could bury injure or kill a person-the avalanche released within the Old snow). Mike relayed that he believes the fracture was mostly wind loaded snow on top of a previous sun crust and that he did not believe there were any impacts of solar warming on that aspect Thursday. Remember that Moderate Danger still means human triggered avalanches are possible.
“Just wanted to send a brief account of an incident that occurred on Thursday feb. 7th.
Three of us, 2 skiers and 1 split boarder, toured up Cascadilla Creek on Thursday morning. Skies were clear and temps just below freezing. We saw many up and down tracks from the previous few days but all traces of tracks were gone by the time we reached open terrain. On the way up Cascadilla we noted a smooth crust underlying fairly light fresh snow. We climbed to the low point in the ridge between Cascadilla and Crystal Creek. Climbing the ridge we noted significant wind loading on the north aspect. The snow below the ridge felt unconsolidated but given the crust and the loading we decided to stay off the steep north slopes. Aside from that we saw no signs of instabilities or recent avalanches. We skied two long runs on the mostly east facing terrain at the head of Crystal. We were careful to avoid the convexities and lee sides of ridges we thought might be cross loaded. The sun was affecting the southern slopes causing a few roller balls but the eastern aspect seemed unaffected. On our third run we traversed further out in to the open terrain and skied down to a prominent point mid slope. We noticed a steep convexity below and discussed the safest way on the skiers right side. the snow boarder rode down and and left to a predetermined spot on a small ridge to spot. I then skied down staying in his track until past the steep roll over and then proceeded about 900 vertical feet to the bottom of the slope. As I was moving to a safer spot the third skier dropped in a little left of the first two tracks and the snow fractured. The crown was about 20 feet wide and maybe 4 inches deep, and only ran a few yards. The triggering skier saw this happening and skied far out right towards some small trees. He inadvertently skied on to an even steeper slope and stopped to look back. As he stopped, the slope he was on fractured a few feet above and he was instantly swept with it. This second crown was about 60 feet wide at the widest, and varied in depth from a few inches to about 2 feet on the skiers right flank. It ran about 300 feet. The skier managed to stay on his feet for about 80 feet and then fell and was dragged about another 100 feet tumbling with the snow washing over him several times. He came to a rest on top of the debris and the snow traveled another 100 feet or so and spread out over the even slope. He was uninjured but lost one pole and a ski. The ski was found about 60 feet below jutting half out of the snow. The pole wasn’t found. It seems that part of the slope was cross loaded from a slight ridge above and south. After debriefing we climbed back to the ridge and more or less followed our skin track out Cascadilla.
Looking back we may have been a bit affected by sunshine powder syndrome and forgot how much tiny aspect changes can affect snow pack. We did not dig any pits but were aware of this particular possible instability and had discussed it several times. Seeing that no one was injured this was a good reminder for us all. If there had been a trap of any sort, there would have been more than enough snow to bury a person. “