From obs: "On the west side of Henderson Moutain, we transitioned to skis and began ascending a low-angle slope toward a known avalanche path. Along the way, we experienced several collapses. Halfway up the slope, Ian noted snowballs rolling down the hill and around the corner, we could see the debris that had come from the steep terrain above. We had a clear view of this slope near the snowmobiles and it had not avalanched when we began ascending. At some point from several hundred feet away, we remotely triggered the slope. The avalanche was ~150' wide, 2' deep and ran almost to the road." Photo:GNFAC