The pilot reported that the windsock at the strip indicated a gusty 30 knot headwind and that he conducted the approach with full flap down and considerable power applied. As he closed the throttle and flared, the aircraft suddenly rolled to the right and dropped to the ground impacting nose wheel first. Later inspection revealed that the nose wheel leg mount had been broken and that the lower firewall and cabin floor had been damaged. Air mass thunderstorms were present in the area at the time of the accident and witnesses at the stip reported a particularly strong gust of wind exceeding 40 knots at the time of the accident. The wind direction was reported to have changed through 90 degrees shortly after the accident.