Two skiers were ascending a northeast-facing avalanche path on the northernmost ridgeline of Mount Blackmore around 1 PM when they triggered a large, dry slab avalanche that failed 3 feet deep, 150 feet wide, and ran 500 feet vertical. Debris piled up 4-8 feet deep. The avalanche failed on weak, faceted snow near the base of the snowpack.
As the group was about halfway up the avalanche path, they saw a small slide initiate to their right and then they heard a loud boom as the rest of the slope collapsed 250 feet above them. The skier lower on the path sprinted to the left into the trees to avoid getting caught. The second skier was 30 higher on the slope. He attempted to run off the slope but was unable to avoid getting captured. He was carried to the bottom of the avalanche path, got submerged in the snow, but thankfully came to rest on the surface. His partner initiated a beacon search and called his name, quickly finding him on top of the avalanche debris. The skier sustained significant injuries. They called 911 and Gallatin Country Sheriff Search and Rescue initiated a response with the Helicopter team. The two skiers worked to address injuries while awaiting rescue. GCSAR inserted a team with a helicopter that provided medical treatment and both the injured and uninjured skiers. The GNFAC was on scene to evaluate the scene for hazards to the rescue team.