Accident: Tri Chutes

Observer Name
AH
Observation Date
Saturday, December 18, 2021
Avalanche Date
Saturday, December 18, 2021
Region
Salt Lake » Little Cottonwood Canyon » White Pine » Tri Chutes
Location Name or Route
Tri Chutes
Elevation
10,200'
Aspect
West
Trigger
Skier
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Soft Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
2'
Width
30'
Caught
1
Carried
1
Accident and Rescue Summary
One skier caught and carried
Snow Profile Comments
Be a dug a pit at 9400 feet facing due west on a 34° slope. ECTX, but we're able to pull the column off at the ice/facet layer 60cm deep. Below this layer were 10 cm of facets then ice to the ground. The faceting and the ice layer were both spatially variable as you moved further southwest the facets would disappear and it would become just ice to the ground. There was a secondary hoar layer 20 cm deep we could get to move with ski cuts but no propagation at this location but in the more exposed areas that hoar layer was not observed.
Comments
Our general plan for the day was to head up the ridge between birthday chutes and try chutes to assess conditions and generally poke around. We done some pets and observed collapsing and cracking on the north and northwest faces, while the west and the southwest faces were generally consolidated and/or scoured/icey.
Once we made our way to the top of Long John Silver, we determined it looked to be the best way out. There were no signs of wind slabs or instabilities, just recycled powder on top of fairly consolidated base. At the bottom of LJS, it got pretty thin so we hopped over to the chute to skiers right. We entered about mid chute and skier one rode the chute clean and got out the exit to the right and out of the way. I dropped after and farmed turns for about six turns, when I noticed a small slab pop about 30 ft below me to the left. At that point I exited hard right and noticed the slab had propagated up to about 100 ft above me. The entire run broke on a roller about 24 in deep from what I could see, and 30 to 40 feet wide. It broke to the ground and ran the entire length and out to the apron, about 500'. The run out covered many farmed tracks and the skin track from earlier that morning. There was a party down below on the skin track but the slide stopped before reaching them. No one else was in the area.
That chutes obviously had some local variability and perhaps had a little more wind loading than the other areas we had skied that day. If we had continued out skiers right and down the less steep slope we may have never even noticed that we had been in danger. Luckily we had looked at that terrain trap and known to exit right if there was any issue, we skied one at a time, there was no one immediately below us, and we had an escape plan. I still feel terrible about having been in this position and potentially putting the people below me in danger, but we approached it one part at a time and executed our contingencies and were able to ski out and no one was hurt.
Coordinates