The California skiing community is in mourning this weekend, after a beloved skier who helped shape a Northern California resort, passed away suddenly during a backcountry run. Bernie Rosow — a Mammoth Mountain skier and snowcat operator — passed away Thursday morning, during a hike up Bloody Mountain in the Sierra Nevada range, near the town of Mammoth Lakes. He was hiking up the mountain with friends, when he suddenly collapsed around 9:30 a.m., according to one of the friends he was with,