On Tuesday, January 19th, two on-duty Yellowstone Club (YC) Ski Patrollers were helping two MSU graduate students collect data for snow science research. They were on private land in an uncontrolled backcountry setting, when, skiing back in-bounds to the YC, one of the patrollers triggered an avalanche.He jumped off a cornice onto a steep (39-42 degrees) wind-loaded slope which avalanched on his second turn. The slide broke 2-4 feet deep, 300 feet wide and carried him through a terrain trap of thick trees. He was partially buried at the toe of the debris 300 vertical feet below. His partners got to him within three minutes, but the trauma was fatal.