On March 23, 2003, about 1250 Pacific standard time, a Ryan Navion, N5291K, veered off the runway and collided with terrain and high vegetation during the landing roll at Mammoth Yosemite Airport, Mammoth Lakes, California. The airplane, owned and operated by the pilot under the provisions of 14 CFR Part 91, sustained substantial damage. The private pilot and one passenger were not injured; however, the remaining passenger received minor injuries. The personal cross-country flight originated at Furnace Creek, Death Valley National Park, California, at 1105, with an ultimate destination of Rio Linda, California. Visual meteorological conditions prevailed and a visual flight rules (VFR) flight plan had been filed and activated. The pilot submitted a statement in the Pilot/Operator Aircraft Accident Report, (NTSB Form 6120.1/2). While en route to Rio Linda they experienced moderate turbulence, and the pilot observed inclement weather along the route of flight. With these factors in mind the pilot decided to divert to Mammoth Lakes airport to wait out the weather. At 1152, the Mammoth Lakes airport automated weather observation station (AWOS) was reporting winds at 200 degrees, 15 knots gusting to 25 knots. The pilot reported that the airport advisory conditions relayed to him were winds of 250 to 270 degrees, 15 knots gusting to 25 knots, and runway 27 was in use. The pilot also observed the airport windsock showing winds from the west/northwest. During the landing sequence, and after the landing gear contacted the runway, the pilot stated that he experienced a "substantial and unexpected gust of wind" from the southerly direction. The left wing raised and the airplane veered off the right side of the runway. The pilot applied rudder and aileron to compensate before deciding to attempt a go-around. The airplane continued to rise in level flight before he "experienced a sensation of downward force." The airplane came to rest in sagebrush approximately 210 feet north of the parallel taxi way.