Ascend Coalpit 4, traverse Thunder Bowl, descend Coalpit headwall, out Coalpit

Full track of Coalpit 4 had avalanched, probably in the last couple of days.  Debris was hard and chunky and track very firm in areas.  Found very loose, granular unconsolidated snow on the treed headwall near the ridge.  We kept this snow in mind as we continued to Coalpit. Found 2"-3"  light powder on sun crust on the route through Thunder Bowl.

Wind was moderate and gusty from the NE on the ridge at top of Coalpit on arrival about 9:00 am.

Three sections of cornice were cut.

No 1.  Resulted in a long running but shallow sluff.
No 2.  Dropped on the slope and stuck with minimal result.
No 3.  Since No 1 veered off a subridge and did'nt run in the gully we planned to descend. We cut a third one that initiated a hard slab avalanche.  Crown up to 4 feet deep and 100 feet +- wide running to the flat at bottom of the upper headwall.  Bed surface was very smooth with faceted snow.  Gouged about 3 feet deeper along the edge of the track near the bottom. 
Wondering if this condition shares characteristics with recent activity in Stairs Gulch and Scotties Bowl.

Photos:  Adam Nesbett