While descending the west-facing Microwave, I unintentionally triggered a wind slab avalanche on a steeper, convex rollover. The avalanche was 30 cms (12") deep and 100' wide. It failed on a sun crust that formed likely Friday. As we were descending the slope, I noticed the west aspect was getting cross-loaded from south winds with a denser wind slab. As I approached a steeper rollover, I cut left to get onto a lower-angled ridge and the avalanche broke 10 meters below me, failing on the steeper rollover.

South winds today were strong and sustained and drifting snow along ridgelines as well as downslope in terrain well-below ridges. I had seen plenty of sensitive wind slabs during the day and descended the west-facing slope that was mostly wind-scoured however it was clear there were also wind-drifted slopes that were being cross-loaded from the south winds.

As this avalanche was visible to the Alta Ski Area, I called Alta Central to report the avalanche and that the scene was clear.

SS-ASu-D1.5