Tropical Storm Jangmi gradually strengthened on Thursday as it moved over the Western North Pacific Ocean southeast of the Ryukyu Islands. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Jangmi was located at latitude 15.7°N and longitude 133.3°E which put the center about 855 miles (1380 km) south-southeast of Okinawa. Jangmi was moving toward the northwest at 13 m.p.h. (21 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 997 mb.
Tropical Storm Jangmi strengthened gradually on Thursday. More thunderstorms formed near the center of Jangmi’s circulation. More thunderstorms also developed in bands in the western and southern parts of Tropical Storm Jangmi. Bands in the eastern and northern parts of Jangmi’s circulation still consisted primarily of showers and lower clouds. Storms near the center of Jangmi generated a little more upper level divergence that pumped mass away from the tropical storm. The removal of a little more mass caused the surface pressure to decrease slowly.
The circulation around Tropical Storm Jangmi was still large. Winds to tropical storm force extended out 175 miles (280 km) from the center of Jangmi’s circulation.
Tropical Storm Jangmi will move through an environment favorable for intensification during the next 24 hours. Jangmi will move over water where the Sea Surface Temperatures are near 29°C. It will move under the middle of an upper level ridge that is south of Japan. The upper level winds are weak near the middle of the ridge and there will be little vertical wind shear. Tropical Storm Jangmi will intensify during the next 24 hours. The large circulation around Jangmi could cause it to intensify slowly at times. Jangmi could strengthen to a typhoon within 36 hours.
Tropical Storm Jangmi will move around the western end of a high pressure system that is over the Western North Pacific Ocean. The high pressure system will steer Jangmi toward the northwest during the next 24 hours. On its anticipated track, Tropical Storm Jangmi will approach the southern Ryukyu Islands in three days.