This was a Wet Slab avalanche unintentionally triggered by a backcountry skier. It was small relative to the path and destructive enough to injure, bury, or kill a person. It broke in wet snow near or on the ground. (WS-ASu-R2-D2.5-O/G). The avalanche broke on a west-facing slope near treeline. The slope angle where the avalanche released was 35 degrees. The slope steepened significantly as the avalanche ran through sparse trees. The avalanche ran about 2000 vertical feet down the chute.

Pertinent Weather & Snowpack

A CAIC forecaster investigated the avalanche on Monday, April 14, two days after it occurred. The snowpack in this area was complicated. On the north side of the avalanche, the snowpack was dry, and layering resembled a Persistent Slab avalanche problem. To the south, where the skiers triggered the avalanche, the snowpack was moist to wet and conducive to triggering wet slab avalanches

Total snowpack depths along the north side of the crown were up to 140 cm. The snowpack layers were dry. On this side of the avalanche, the avalanche broke on a thin, fist-hard layer of 4 mm facets that was buried around December 9, 2024. The top 30 cm of the snowpack was composed of melt-freeze crusts. Just below the crust, there was an ice formation where meltwater pooled at some point. Investigators could not determine if meltwater moved below the ice formation into the faceted layer because all of the layers were dry, and percolation columns were not evident. The north side of the avalanche resembled a dry Persistent Slab avalanche.

The snowpack on the south side of the crown was much shallower, with a snow depth of just 71 cm, or about half the depth of the north side. Below 1 to 2 cm of new snow, there was a 16 cm-thick hard melt-freeze crust. Below this melt-freeze crust were moist to wet faceted crystals and depth hoar. These weak grains had clearly lost strength due to meltwater moving through the snowpack and to the ground. This snowpack structure on this side of the avalanche was a Wet Slab avalanche. Skier 2 triggered the avalanche directly below where this snowpit was dug.

Notably, investigators found ski penetration only a few centimeters deep, while boot penetration was to the ground. The party involved in the avalanche noted a crusty snow surface and minimal ski penetration before they triggered the avalanche.

Accident Summary Four skiers (Skiers 1 through 4) left the Breckenridge Ski Resort at the Peak 6 backcountry access point at around 11:45 AM on Saturday, April 12. They planned to ski the K Chute of the Sky Chutes, a series of steep, westerly-facing avalanche paths that drop down the west side of the Tenmile Range. The group discussed the avalanche forecast, and they all carried avalanche rescue gear. The group had left a vehicle in a parking area below the Sky Chutes earlier that morning.

The group walked down mostly bare ground from the ridgeline to the top of K Chute. The group put skis on and skied the upper low-angle snowfield together for a few turns. They described the snow conditions as crusty. When they stopped, the group wound up in different spots before entering steeper terrain. Skier 1 radioed the group to discuss descending the section. Skier 2 descended next and had made several turns past Skier 1 when he triggered the avalanche. The avalanche broke above Skier 2 and swept him down the path.

Skier 1 lost sight of Skier 2 and began to descend the path. Skier 1 got his avalanche transceiver out and also communicated with Skier 3 on the radio. He asked Skier 3 to call 911, letting him know he was beginning to search. Skier 3 did not call 911 due to miscommunication. After a few minutes, Skier 1 spotted Skier 2 in the still-moving avalanche debris. Skier 1 watched Skier 2 move to the left and out of the debris as the avalanche slowed down.

Skier 1 reached Skier 2, approximately 1100 vertical feet from where Skier 2 was caught. Skiers 3 and 4 reached Skier 2 a short time later. Skier 2 was injured but not buried. He had lost both of his skis in the avalanche. Skier 1 assisted Skier 2 in walking down the gully to the skier’s right side onto bare ground. They continued to descend, walking on bare ground. Eventually, they ran out of bare ground and were postholing in soft, wet snow, making travel very difficult. The group realized that Skier 2 had another set of skis in the parking area near the bottom of the path. Skiers 3 and 4 went to retrieve the skis. At the parking lot, they realized they didn’t have climbing skins, and postholing back up the path was too difficult with the snow conditions. Skier 1, who was carrying climbing skins, left Skier 2, descended to the car, retrieved Skier 2’s other skis, and re-ascended to where he left Skier 2. Despite injuries, the two skiers were able to ski down to the car, where they met Skier 2’s spouse, who transported him to the hospital.

Around 2 PM, a second group of two skiers left the Breckenridge ski area from the same backcountry access point with the same goal of descending K Chute. When the two skiers reached the top of the K Chute, they saw the crown of the avalanche. They weren’t sure when it had occurred. They had a photo from earlier that morning and realized the avalanche wasn’t there at 8:30 AM. The two skiers descended the path with their avalanche transceivers in search mode. They found and transported Skier 2’s skis as they descended. A third group descending the K Chute also conducted a transceiver search of the avalanche debris.

The searching groups reached the bottom of the avalanche debris without detecting a transceiver signal. They called 911 to ask if the avalanche had been reported. They were told it had not been. The Summit County Sheriff's Office and the Summit County Rescue Group (SCRG) were dispatched to the scene. As the rescue group organized, they were alerted by St. Anthony Summit Hospital in Frisco that they were caring for a person caught in an avalanche in the Sky Chutes. SCRG matched the skis found in the K Chute with the description of Skier 2’s skis.

Comments

We do our best to describe avalanche accidents to help the people involved and the community as a whole better understand them. We offer the following comments in the hope that they will help people avoid future avalanche accidents.

The group read the avalanche forecast, discussed it as a group, had rescue gear, and made a good plan based on the forecast. Wet Slab avalanches were not in the avalanche forecast. It is important for backcountry travelers to remember that regional avalanche forecasts are a starting point for the day, and on-the-snow continued assessment is crucial. This was the first reported Wet Slab avalanche in Summit County since March 27 (in over two weeks) and only the fourth reported Wet Slab avalanche in the Northern Mountains of the season. On the day of the accident, there were very few places where backcountry travelers could have triggered this type of avalanche. The slope needed to be west-facing, near treeline, with a snowpack less than a meter deep, in constricted terrain with darker objects above the path, like trees or rocks, to help melt snow more quickly and increase meltwater production.

The group found that the snowpack was supportable to skis as they descended lower-angle terrain. When dealing with wet avalanches, it is important to get out of your skis, board, or machine to check how far your foot penetrates into the snowpack. This test may have led the group to find wet, cohesionless snow beneath the one-foot-thick slab of re-frozen melt forms before committing to the steep terrain where they triggered the avalanche. Because they were descending the avalanche path from the top, they had not assessed conditions in similarly steep terrain before Skier 2 committed to the slope.

During the stressful rescue, the group mentioned calling 911 but did not due to miscommunication within the group. Several hours later, other groups found skis in the path, a large debris pile, and no transmitting transceiver signal. They did call 911. Luckily, personnel at the hospital alerted Summit County that they were caring for an avalanche victim, preventing an extended, resource-intensive search and rescue effort.