 After forming , the depression tracked generally westward due to a subtropical ridge to the north . Around that time , it was still located within the monsoon trough , and it interacted with another circulation to its east @-@ southeast , causing a motion to the west @-@ northwest . As it moved away from the other circulation , the depression was able to intensify , and the wind shear decreased . On June 13 the JMA upgraded the depression to Tropical Storm Soudelor to the east of Samar Island in the Philippines . That day , the Philippine Atmospheric , Geophysical and Astronomical Services Administration PAGASA initiated advisories and gave it the local name " Egay " . Upon becoming a tropical storm , Soudelor developed rainbands to the north and south , although it could not intensify significantly due to a tropical upper tropospheric trough to the east . A mid @-@ latitude trough to the north weakened the ridge , which allowed Soudelor to turn more to the northwest off the northeast coast of the Philippines . The circulation became exposed from the deepest convection , and around that time the storm was located about 160 km ( 100 mi ) east of Samar Island . Thunderstorms gradually increased , and the outflow improved . Late on June 16 , the JTWC upgraded Soudelor to a typhoon , and the next day the JMA followed suit when the storm was located southeast of Taiwan . 
