A group of 4 skiers were ascending a low angle ridgeline above the warm lake summit road. On the way up the ridge, we experienced frequent large collapses. At an elevation of approximately 7700’, we felt a large collapse and soon after observed a remotely triggered hard slab avalanche across a gully from where we were traveling. The closest part of the crown was approximately 250’ from us to the climbers right and was on a northwest aspect. The crown was just below a rocky ridge and extended around to a heavily corniced adjoining ridgeline.
This is a gully feature where avalanche activity has been observed multiple times in the past. We heard the mountains talking and continued ascending via our chosen ridgeline climbing route to our high point and took our alternate low angle ridge descent route. We chose to avoid avalanche terrain for the rest of the day. This was a good reminder of the variability that can exist just of the outside the perimeters of the forecast area. We also observed large natural avalanches across the valleys at similar elevation (see picture).