Avalanche: Turnagain

My friend and I were climbing towards Magnum going the southern, more gentle route. We noticed four skiers/boarders (not sure) climbing the ridgeline on cornbiscuit. At about 13:00, one of four started descending down a steep snowfield to the north, and in the shadow, of the ridge. The moment he hit the slope, a huge section of the snowfield fractured and started coming down with quite a rumble in a soft slab avalance. The skier was able to stay above the slide and did not get swept up in it. Once things settled out, he skied down the slide channel and just off to his left of it. Skier then turned left (our right) leaving the valley to meet up with his three friends who had come down the ridge line. There was another witness below us who got a much better look. I took some pictures afterwards.