 Forming in tandem with Irving , Judy formed east of the Philippines as a tropical disturbance on September 4 . In contrast to Irving , Judy 's intensification was more rapid , becoming a tropical depression early on September 6 , a tropical storm later that morning , and a typhoon on September 8 while tracking northwestward . On September 9 , Judy appears to have ingested dry air from a nearly tropical upper tropospheric cyclone , as its central eye feature expanded significantly . A mid @-@ latitude trough south of Korea swept Judy more northward , ultimately accelerating the storm towards Japan on September 11 . When the 70 knots ( 130 km / h ) Typhoon Judy hit southeastern Japan on September 12 , its torrential rains left 25 dead and causing moderate damage . Extratropical transition had begun around that time , and Judy became an extratropical cyclone on September 13 . 
