 After forming , the depression tracked northwestward , influenced by a ridge to the northeast , although it briefly turned to the northeast due to an increase in westerly winds ; however , its northwest motion quickly resumed . A trough over the Philippine Sea increased outflow over the depression , and the convection became better organized . Early on June 29 , the JMA upgraded the depression to Tropical Storm Rammasun . While moving northwestward , the circulation initially remained broad and disorganized , located east of the cycling convection . However , Rammasun steadily intensified , and an eye developed on July 1 . That day , the JMA and the JTWC upgraded the storm to a typhoon about 930 km ( 575 mi ) east of Luzon in the Philippines . The typhoon continued strengthening , developing concentric eyewalls with well @-@ defined rainbands . At 1500 UTC on July 2 , the JMA estimated peak 10 minute sustained winds of 160 km / h ( 100 mph ) . Early on July 3 , the JTWC estimated 1 minute sustained winds of 205 km / h ( 125 mph ) about 350 km ( 220 mi ) south @-@ southeast of Okinawa , or 510 km ( 315 mi ) southeast of Taiwan . 
