Tropical Storm Champi developed west of the Marianas on Tuesday night. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Champi was located at latitude 15.3°N and longitude 139.9°E which put it about 320 miles (515 km) west-northwest of Guam. Champi was moving toward the west-northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1000 mb.

The circulation around former Tropical Depression 06W strengthened on Tuesday night and the Japan Meteorological Agency designated the system as Tropical Storm Champi. More thunderstorms formed near the center of Tropical Storm Champi. The inner end of a rainband wrapped around the eastern and northern sides of the center of Champi. Other bands of showers and thunderstorms were revolving around the center of circulation. Storms near the center generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 50 miles (80 km) from the center of circulation.

Tropical Storm Champi will move through an environment favorable for intensification during the next 48 hours. Champi will move over an area where the Sea Surface Temperatures are near 29°C. It will move between an upper level low northeast of the Marianas and and upper level ridge over eastern Asia. The upper level winds are weak between the upper low and the ridge and there will be little vertical wind shear. Tropical Storm Champi will intensify during the next 48 hours and it could strengthen to a typhoon.

Tropical Storm Champi will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next 48 hours. The high will steer Champi toward the north during the next several days. On its anticipated track Tropical Storm Champi could be southwest of Iwo To in 48 hours.