Steamboat & Flat Tops

Avalanche

We witnessed two soft slab avalanches release on the same slope simultaneously, remotely triggered by a snowmobiler. The larger of the two avalanches was small relative to the path but large enough to bury, injure, and kill a person (SS-AMr-R2-D2-O). The smaller of the two avalanches was very small relative to path and had less destructive potential (SS-AMr-R1-D1.5-O). We estimated the larger avalanche averaged a crown depth of about 3 feet deep, ran 225 feet wide and 250 feet long, with a vertical fall of about 150 feet. These two avalanches occurred on an east aspect below treeline, on a sparsely treed, rocky knoll-like feature. The slope was likely wind loaded. Two snowmobilers rode on top of the feature and triggered a long shooting crack, and about 5 minutes later as other snowmobilers rode near the terrain, the two avalanches occurred.