Wind slabs over a weak layer

We skied up the Throne and encountered serious wind effected terrain. Some slopes were blown clear, others has ripples of sastrugi, and yet others were wind-loaded. After a pit down low yielded nothing significant, we skied higher to look for wind-loaded slopes. We found a natural crack that occurred in a wind slab, and then we dug near the ridge at a spot we typically descend. We got an ECTP9, an unstable test result. The video shows it well. Wind loads are isolated, but they could avalanche. They are easy to find: they were the only smooth parts of the slope.