We were aware of spooky conditions and travelled very cautiously to gain the ridge. Our goal was a well anchored area of rooster comb where we believed there would be an opening in the cornices and no opportunity to produce a large avalanche based on our terrain selection. The weather was below freezing with heavy clouds and moderate fog, preventing solar but also reducing visibility significantly.
From the side as we approached along the ridge, the area where we intended to drop appeared fully attached to the slope. No overhang or curl as we had seen the cornices as we travelled the ridge. This may have been an optical illusion due to poor visibility, or it may have been a wind loaded shelf that we misjudged.
As we regrouped, still everyone 5-6 feet or more from the edge, the snow collapsed suddenly and violently. Our group was 5 people, spaced out but close enough together to trigger the release.
4 of 5 fell with/behind the cornice. 1 person remained above and had eyes on the situation. 3 people were able to gain control and stop sliding at the top the slope. 1 person was carried appx 20 feet and was able to grab a tree before momentum was gained. No serious injuries were incurred.