 Pat became the lone tropical cyclone in the western Pacific basin during the two @-@ month interval between Odessa 's dissipation and the formation of Ruby . The disturbance which led to Pat 's formation developed southwest of Guam on May 14 . By May 17 the system had organized sufficiently to become a tropical depression . Moving westward until the afternoon of May 18 , Pat abruptly changed course to the north through a break in the subtropical ridge parallel and close to the Philippines . Rapid intensification ensued , with Pat reaching its maximum intensity late on May 21 . As the cyclone turned to the northeast , vertical wind shear began to weaken the cyclone . Its wind field broadened as it began extratropical transition . By midday on May 23 , Pat had evolved into an extratropical cyclone along a frontal boundary with cool , dry air wrapping into its center . The cyclone became absorbed by a larger system near Japan on May 24 . 
