Johnson Canyon

Given today's advisory and recent avalanche activity, our plan was to hike around Johnson Canyon, do some beacon practice, look at the snowpack, and stay away from avalanche terrain. That turned out to be the right plan. The usual cornices had formed on the east facing ridge in the middle of the canyon @7200', with some cornice chunks on the slopes below that broke off during yesterday's storm. I stomped on some of the remaining sections of cornice, which were pretty stubborn and hard to break. On an east facing wind-loaded test slope close by, I stomped hard several times looking for a reactive wind slab. On the 3rd or 4th stomp, instead of wind slab cracking, the slope collapsed with a clear whumpf. My partner on the ridge 10 feet above me felt the snow he was standing on drop 1-2 inches. We wrapped around the back of the canyon to check out the low-angle north facing slopes. I skied down a few hundred feet, then stopped to wait for my partner. After his 2nd turn, ~200 feet away from me, the slope collapsed and I heard/felt a loud whumpf. Very spooky. No cracking was visible from that location. We dug a quick pit to see what we could see (Pic 1). The top few inches was a 1F-P hard slab of heavy/wet snow from yesterday's storm, with an inch or two of slightly lower density (4F) snow below that from the colder start to yesterday's storm. Below that there was about 2 feet of 1F snow from the prior few storms, and the obvious facet layer around the December rain crust below that. We suspect the slope collapsed on the Jan 2 buried surface hoar. While skinning back up we finally saw cracks near the sides and top of the slope we had just skied (Pic 2), suggesting that the entire ~300'x400' slope had dropped as a single slab.

Quick report