Avalanche in Gore and Elk Mountains/central Mountain Valleys, Colorado

All information paraphrased from the Colorado Avalanche Information Center report on the incidence. The fatal avalanche was triggered by a solo backcountry skier in an area known locally as Boss Basin, in the area of Vail Pass, CO. Boss Basin is comprised of a series of northeast-facing slopes that are low-angled at the top, descending into steeper slopes below, ending at a flat bench. Conditions in the Vail Pass area on the accident day were rated by the Colorado Avalanche Information Center at Moderate (3/5) near and above treeline, with a Considerable (2/5) rating below treeline. The main concern was listed as Persistent Slab Avalanches, favoring slopes northwest through north to northeast facing at all elevation bands. The likelihood was listed as Likely, and size expected listed as Large to Very Large (up to D3), meaning these avalanches would be capable of burying, injuring, or killing a person as well as potential bury cars and break trees. The avalanche forecast also included wording stating that humans could easily trigger avalanches where [they] find more than about 10 inches of snow, that avalanches that break on buried weak layers would be difficult to survive, and that remote triggering of avalanches would be possible. The backcountry skier that triggered the fatal avalanche, referred from here on as Skier 1, started the day at approximately 7AM local time in the Vail Pass Winter Recreation Area. Skier 1 used a snowmobile to access various terrain through the morning before heading toward Boss Basin around 1:15 PM local time, parking his snowmobile at the top of a nearby ridge. Skier 1 successfully made one descent and climbed back up the slope for a second. On the second descent, Skier 1 triggered the avalanche and was caught and buried near the toe of the avalanche with only the tip of one ski visible. As Skier 1 was alone, no rescue action was taken until family members noticed they were overdue at approximately 11:30 PM local time that evening. Members of Summit County Rescue Group searched through the night, finding the accident location by 6:00 AM local time the next morning. Two rescuers and a search dog were at the avalanche location by 8:00 AM, and the dog quickly alerted on an area of interest. In this location, the rescuers located Skier 1, now deceased, with their head buried approximately 1 foot below the snow surface. Skier 1 was dug out and eventually removed from the location by helicopter.

The historically poor snowpack across Colorado through the 2025-2026 Winter season allowed for a shallow, weak snowpack to develop in the accident location. Recent fresh snowfalls in the weeks prior to the event allowed for a layer of soft, fresh snow to develop atop a stronger layer of storm snow, which was itself on top of the weakened initial snowpack. Strong winds in the days leading up to the fatal avalanche also provided wind-loading issues, continuing to weaken the overall snowpack conditions. Avalanche conditions in the Vail Pass area, where the fatal avalanche occurred, were rated at Considerable (3/5) at and above treeline, and at Moderate (2/5) below treeline.