Skier triggered wind slab avalanche on North West facing slope between birthday chutes and tri chutes in whitepine canyon. This was clearly a wind slab formed from the deposited snow in a small concave area. The slide broke when skier cut across into the area with deposited snow. The slide broke about 15 feet up from skier and continued to run for about 300 vertical feet. Skier was caught and carried About 200 vertical feet but was not buried or hurt.