The pilot reported that, during the landing as the tailwheel began to settle, a "massive and unexpected gust of wind" lifted the left wing. He immediately attempted to recover by adding rudder inputs; however, the wind shifted to a "quartering tailwind," and the rear of the airplane whipped rapidly to the right. He applied the brakes as the airplane encountered a downhill slope on the left side of the runway, and it then came to rest inverted. The airplane sustained substantial damage to the empennage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The automated weather observation system located on the airport reported that, about the time of the accident, the wind was from 360° at 12 knots, gusting to 17 knots. The pilot landed on runway 35L.