Triggered a medium-sized soft slab avalanche coming out onto the apron of the little chute at the top of west porter, was able to ski off the slab skiers' left easily. We were traveling 1-at-a-time in this terrain, and had someone who opted not to ski the chute already spotting us from below. The slab ran maybe 200' and produced a debris pile probably not big enough to have buried a person, but bigger than I expected. No pics, very cold hands.