On June 11, 2000, about 1530 Eastern Daylight Time, a homebuilt Falcon XP, N544AA, was substantially damaged while taxiing at the Orange County Airport, Montgomery, New York. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local flight conducted under 14 CFR Part 91. According to the pilot, he had been conducting functional tests on the airplane in the airport traffic pattern. After landing, the pilot observed signs of thunderstorms in the area, and decided to make two shorter flights down the length of the "shorter, active runway." When the two flights were completed, the airplane was taxied back toward the ramp area. While taxiing, the pilot realized that the wind, which was blowing from a direction behind the airpane, began to increase and "my indicator showed no froward air movement although I was doing 45 mph." Dust and grass started to blow by the airplane, and the controls were being forced from behind. As the pilot made a 180-degree right hand turn on the taxiway to the ramp, a squall pushed the airplane sideways, lifted the right wing up, and rotated the airplane on the left wing tip. The airplane nosed over and came to rest inverted. The pilot estimated that the winds at the time of the accident were in excess of 60 mph. The winds reported at the airport, at 1454, were from 260 degrees at 8 knots, gusts to 18 knots, variable from 220 degrees to 280 degrees. The winds reported at an airport 7 miles to the east of MGJ, at 1515, were from 320 degrees at 14 knots, gusts to 20 knots. At 1545, the winds were from 320 at 12 knots.