Avalanche occurred as a result of Dec 26-27 storm event that produced 19" of snow at 2.6" SWE. Failure is assumed to be on a known persistent weak layer of facets 30-40 cms above the ground that formed during the November high pressure. Cross wind loading over the terrain feature was a contributing factor. This is a rare aspect for a faceted persistet weak layer. Stability tests performed that day confirmed a reactive weak layer on southerly aspects.