1st run of the day, about 8 am. Cold, no sun yet, soft dry powder surface from yesterday's storm. The first skier on a ~ 38 deg slope triggered a sluff that grew in size and caught him from behind in a steeper choke that increased the speed and depth of the sluff, causing a tumbling crash and a short carry. He stopped, the sluff continued to much lower angle terrain, with no injuries or lost gear. The debris was shallow enough that a full burial was very unlikely and the skier chose not to deploy his airbag trigger, but the sluff was fast, far running, and entrained a lot of snow. It would have very easily carried a skier over a cliff or into trees. Two other lines were skied, one NE facing and one NW facing, and on both we easily triggered sluffs capable of damage but total suckers for ski cuts. Noteworthy was that this took place on shady slopes with cold temps - these were not wet slides and emphasized that the new cold snow on the wet surface skied well but bonded poorly to the old wet surface from 2 days ago.