This avalanche ran during the Feb 20 storm event that put down 14" of new snow capping off a week long storm event that totaled 18" at 1.2" SWE. Strong SW winds early in the cycle built pencil hard slabs 2'-3' thick on N and E aspects at treeline and above. These were resting on the previous week's 5" that preserved the Feb 11 faceted layer. Stability tests and an intentionally triggered slide early in the week indicate that failure first occured on the Feb 11 weak layer before stepping down into facets beneath the Christmas Rain Crust and or going to the ground. The majority of this well connected slab was on a north aspect but it propagated around the cirque encompassing east and southeast aspects as well.
This avalanche was first noted in an observation by Sam Van Wetter on Feb 20.
Sam Van Wetter photos.
