On April 17, 1997, at 0936 hours mountain standard time, a North American SNJ-5, N9013A, ground looped after landing at Falcon Field, Mesa, Arizona. The airplane sustained substantial damage, and there were no injuries to the airline transport pilot or the passenger. At the time, the tower reported a 90-degree crosswind from the right. The flight departed Falcon Field at 0915 hours on a local area personal flight. No flight plan was filed and visual meteorological conditions prevailed. The pilot stated that there were some buildings adjacent to the landing runway that were obstructing the surface wind such that there was no noticeable crosswind at touchdown. However, as the tail wheel touched down, wind from between the buildings caused the airplane to suddenly weathervane to the right and depart the hard surface runway into soft dirt where the right main gear dug in and broke away from the airframe. The pilot further stated that in this model, the tail wheel is unlocked by moving the control stick forward. Since he made a wheel landing, he thought that he may have pushed the stick forward enough to unlock the tail wheel and then did not get it back into the relock range before encountering the sudden onset of the crosswind.