Quick report
At approximately 1300 observed a skier triggered D1 wet slab avalanche on a Northeast aspect, specifically more easterly facing wall of gully, of South Peak at 10900 ft elevation. Skier not carried. Ran out approximately 450 feet. Recent 12-18 inches snowfall 3 days prior. On ascent, no signs of instability. No rollerballs or pinwheels. Temps around 35-40 degrees though cold wind out of the north with mostly cloudy skies. Cautiously traveled uphill sampling snow as we went. Apart from rocky/snow peak, 1-2 inch crust above several inches of cold, soft snow. Peak showed signs of wet snow evolution. However, we did not ascend through (or sample) the more easterly wall of gully where slide occurred. Remainder of descent continued to be supportable, cold powder. No injuries. Upon returning to car, many wet loose slides visible on Northwest aspect of South Peak.