Persistent slab avalanche on Nyack Mountain

This avalanche occurred either Friday night (1/12) or early Saturday morning (1/13) following a storm that deposited 18" of heavy dense snow at 6000' in nearby Wahoo Creek.

• The avalanche started at 7500' on Nyack Mountain and was triggered by the heavy dense snow and/or the associated storm slabs directly above the crown.
• Failure layer was weak faceted snow resting on a crust deep in the snowpack. Numerous rock outcroppings with associated weak snow are scattered across the face of Nyack Mt and the fracture line.
• The crown varied from 2 feet to over 7 feet.
• Of note was the ability of this slide to pull out a deep 8-10' slab off a low angle ridgeline.
• Debris from this initial slide then triggered a Persistent Slab avalanche 1000 vertical feet below and off to the side of the path.
• Most debris stopped at several terrain traps in the path but a relatively small amount traveled the entire 3500' to the valley floor.
• Numerous storm slab avalanches were observed on either side of the path at upper elevations. 
• Oddly, limited avalanche activity was noticed in the other slide paths that I could see in Rescue Creek.