On August 8, 2001, approximately 2100 mountain daylight time, a Piper PA-24-250, N699WL, registered to and operated by the private pilot as a 14 CFR Part 91 personal flight, collided with a tree just prior to landing at Thompson Falls airport, Thompson Falls, Montana. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged and the private pilot and passenger were not injured. The flight departed from Great Falls, Montana, about one-and-a half hours prior to the accident. In a written statement, the pilot reported that during the flare for touch down, a sudden gust of wind lifted the left wing and "pitched the plane over at 90 degree angle and up." The pilot applied full power in an attempt to stabilize the upset. The stall horn sounded and the aircraft drifted to the right side of the runway. The pilot was successful in lowering the nose of the airplane when the left wing struck a pine tree. The airplane descended to the ground, collapsing the nose and left main landing gear. The airplane spun around about 180 degrees before coming to rest. The pilot reported no mechanical failures or malfunctions with the aircraft at the time. The pilot reported the wind from 70 degrees at 10 to 15 knots.