Chockstone couloir fan

Skinning up Chockstone couloir to see how it’s filling in. Near the choke of the couloir we felt a small whumpf followed by a massive whumpf and shooting cracks propagating from a thin snow covered rock across the slope 10m above skier. Felt like the entire snowpack settled on the basal facets. 1cm fist snow wind skin forming in open areas. Observed a new natural dry loose 1.5 across the valley on the way down at 1315. Apx 2350m elevation ran 35-40m on a S.W. aspect. Sky was broken precip nil winds light and variable with an air temp of -2.4.