From an email:
"Dug a pit at ~9000’ on a NE as aspect got a ECTP29 at 56cm down, breaking below the new snow and a 12cm knife-hard sl slab Broke on small facets (<1mm) in between wind slabs. I marked the tr trigger point n red. Skinned up a low angle gully up to around 9500’. As I got near the steepest part of the gully (38°), a soft slab slab 8” thick propagated 100’ wide and slid 500’ back down to my pit. No one was caught. Contrary to my pit, this ENE aspect slid aspect the new snow on top of a previous wind slab. wind slab on the bed surface bed surface snow/old snow interface. Found safer skiing down low in the trees where there was less wind loadin wind loading