 Initially , the depression was expected by the JTWC to move north before accelerating towards the northwest . On August 17 , the JTWC upgraded the depression into a tropical storm . At this time , the agency anticipated Thad to re @-@ curve well east of Japan . By 0000 UTC on August 18 , the JTWC upgraded Thad to typhoon status as the cyclone developed a ragged eye . Six hours later , the JMA followed suit . During the evening of August 18 , the agency estimated that Thad reached its peak intensity of 80 mph ( 130 km / h ) and a minimum barometric pressure of 955 mbar ( 28 @.@ 2 inHg ) . Early the next day , the JTWC estimated peak winds of 100 mph ( 160 km / h ) . According to the JMA , Thad would maintain its peak wind speed until August 21 , when the storm weakened slightly . However , the JTWC suggested that Thad began to deteriorate on August 20 . The next day , forecasts from the JTWC indicated that the typhoon was expected to re @-@ curve and accelerate due to a trough located south of Japan . However , since the trough moved into the Sea of Japan instead , a subtropical ridge developed east of Typhoon Thad . On August 22 , however , Thad accelerated northward in the general direction of Japan . At 0000 UTC on August 23 , the JTWC downgraded Thad into a tropical storm while moving onshore in central Japan . Several hours later , the JMA followed suit , even though Thad had moved well inland by that time . By this time , cooler air had taken toll on the storm , and that afternoon , data from both agencies indicated that Thad finished its transition into an extratropical cyclone . By that time , Thad merged with a trough over the Tatar Strait . However , the JMA continued monitoring the system until the morning of August 25 . 
