On Saturday Dec 17 I hiked from the Dry Creek Trailhead in Alpine to Horsetail Falls. From the trail, I could see a small avalanche on the south east face of Bighorn Peak. I did not see it triggered, so I don't know when it occurred. If you look to the right of the bottom of the avalanche, you can see what looks like a ski track from someone skiing down from Lake Hardy. The track is pretty far from the avalanche site, so it seems unlikely to me that it was triggered from below by whoever made the ski track.

Looking at the picture I took and a map, I estimate the slide elevation was somewhere between 9,400 and 10,000 ft.