This avalanche was one of several observed on northerly facing aspects surrounding South Mountain the day after a prolonged storm event that produced 20"-30" of snow at 2"-3" SWE, accompanied by strong NW winds over a 12 hour period. A known persistent weak layer of facets in the lower portion of the snowpack has been well documented throughout the season and the overall depth, width, and apparent connectivity of the slab makes it seem likely that this avalanche failed on that layer.