All the fracture lines blown in.  Most everything in the upper cirque from the Pfeifferhorn to Redbird Pk had a fracture line.  Likely occurred overnight.  Only one collapse on a wind loaded wind-roll.  Otherwise skiing through thin rain crust with bottomless squares below.  1-2mm rain crust up high,  3cm friable crust down low.  Facets noted beneath mid-elevation crusts...

Photo below of collapse/crack and the upper headwall.