At approximately 13:45 on Jan. 21, 2016, two people riding two abreast on a snowmobile unintentionally triggered a large soft slab avalanche. The avalanche broke approximately 3 feet deep, 500 feet wide, and ran 250 vertical feet, and into old snow layers (SS-AMu-R3-D2-O). The slab failed on a layer of facets above a thin melt-freeze crust (Jan 14th crust). The slope varied between 32 and 42 degrees in steepness, and released on an east southeast slope near treeline at 11,000 feet. One of the riders was buried in a tree well. Members of the group responded and extracted the rider. Guides from a cat ski operation in the area responded, provided medical care, and evacuated the rider from the field. Emergency medical services transported the rider to medical facility where he later succumbed to his injuries.