Wind Slab and Cornice Failure on Grouse Rock

My partner and I went out for an afternoon tour (non-guiding personal tour) to check out the new snow and make our first turns of the season. There were lots of tracks in the Grouse area, and we were surprised by the excellent coverage. As we neared the top of Grouse rock, there were signs of prior loading, including a large cornice failure that appeared to have failed during the tail end of the storm. We noted the size of the blocks as well as their hardness (pencil).

We reached the ridge, transitioned, and chose to descend via the lower-angle part of the saddle and through existing tracks that had chopped up the snow. My partner descended first, and enjoyed great turns into the trees. I took a line about 5' higher into fresh snow, expecting a bit of a wind slab to break off below my skis. As I turned back, I spotted cracking out of the corner of my eye (opposite the direction I was turning) and stopped to witness a decent sized wind-slab pocket pull loose and run into the trees below. While the pocket was reasonably small (~30' wide), the crown was roughly 18" deep and the fracture propagated upslope into the steeper terrain we were intentionally avoiding. 

We continued skiing through the trees, avoiding the steep mid-slope roles in the NE terrain of Grouse (that are quite thin at this point in the season). Coverage is thin but obstacles are avoidable with cautious skiing.