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, Christian Pondella (via SF Gate ). Bernie Rosow passed away on Thursday, during a morning hike up Bloody Mountain in the Sierra Nevada range. Instagram/@bernierosow “Everything was normal, just a typical day. Just out of the blue he said, ‘My back hurts, it hurts between my shoulders,’” Pondella told the outlet. Pondella said that he sat down and stopped responding to questions, adding, “it happened so quick.…