Observer Name
Little, Hoffman, Hardesty.
Observation Date
Monday, January 30, 2023
Avalanche Date
Monday, January 30, 2023
Region
Salt Lake » Little Cottonwood Canyon » Flagstaff Ridge
Location Name or Route
Flagstaff Shoulder
Elevation
9,900'
Aspect
Southwest
Slope Angle
40°
Trigger
Skier
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Soft Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
2'
Width
100'
Vertical
300'
Snow Profile Comments
Similar to what we found while digging on south and southeast aspects, yet the crusts were more pronounced. The upper crust was more variable and friable, with small grain facets lying above and below. The avalanche failed above this crust, on facets, however in places(picture #2 below), stepped down to the facets above the deeper crust. On a southeast facing aspect where we dug earlier in the day, around 9,000 feet, we had variable results, from the most sensitive being ECTP 18 down 60cm from the surface below the upper crust. Other pits at the same aspect and elevation yielded ECTPN results of a similar number. We did not feel comfortable doing more than a quick crown profile due to lingering overhead hazard with the concern for other skiers descending on top of us and releasing the remaining hangfire. Height of Snow at the site of the crown profile was 160cm. If we had not skinned up the debris for a purpose of a beacon search, we probably would not have gone up to the crown.
Comments
SS-AS-D1-R1. While skinning up towards Pole-line/Cardiff pass, we noticed a small avalanche on the southwest side of the Flagstaff shoulder with one ski track entering the crown, and we were unable to see any ski tracks exiting the debris or slope. We shifted directions towards the avalanche, and once at the bottom still could not see any tracks exiting. Despite the small size of the avalanche, we were concerned about a potential hangup in the trees within the path for the involved party. We decided to send two from our group of 5 up to perform a transceiver signal search because it appeared that the individual may have been traveling alone. The remaining group members stayed in the flats, keeping eyes on the hanging snow above, and called Alta Central to inform them of the situation, so Alta Ski Patrol could standby if the signal search yielded results. We turned our beacons to search at the toe of the debris, and continued to switchback up the slope, spacing out ~50 feet. The debris in the open snow, for the most part, was not deep enough to bury a human. On the trees there was debris piled up to 7 feet deep.
After we reached the stauchwall(roughly) we were finally able to see a ski track exiting to the skier's right, through the trees, traversing far out on the slope away from the avalanche. Given the traversing nature of the track, it was almost impossible to see from a downhill angle. At this point, we put our transceivers back into send, and communicated the info back down to the rest of our party below so they could communicate back to Alta Central. Out of an abundance of caution, we sent one skier up to the uppermost trees, the last point where anyone involved in the avalanche could have been pinned. It seemed that the involved party had indeed arrested, pinned, or otherwise stopped against these trees, and then skied out. Hard to tell exactly, but this is my best guess. From here I traversed over to the crown to perform a quick profile, then skied back down to the rest of the group. Picture of the trees from uphill included below. Thankful there wasn't any serious involvement in this avalanche!
Photos below:
Comments
Photo 1: The whole scene, our skintrack up, and ski tracks down. If you look closely, you can see the involved parties exit track on the right side of the trees.
Photo 2: Crust step-down below the crown.
Photo 3: Looking up at the crown from the upper trees.
Photo 4: looking down at the upper trees
Photo 5: another photo of the avalanche
Coordinates