The pilot reported that he was departing to the north from a snow covered grass runway in a ski-equipped tail-wheel airplane. A plowed asphalt runway intersected the snow covered runway, and snowbanks were located on the north and south side of the plowed runway. The pilot reported that during takeoff, the airplane impacted the snowbank on the south side of the asphalt runway and nosed over. The airplane sustained substantial damage to the fuselage, wings, and empennage. The pilot reported that there was no malfunction or system failure of the airplane before the accident.