Typhoon Jangmi was approaching Okinawa on Sunday. At 11:00 a.m. EDT on Sunday the center of Typhoon Jangmi was located at latitude 23.3°N and longitude 127.7°E which put the center about 255 miles (410 km) south of Okinawa. Jangmi was moving toward the north at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 85 m.p.h. (135 km/h) and there were wind gusts to 105 m.p.h. (165 km/h). The minimum surface pressure was 973 mb.
The northern part of Typhoon Jangmi was already affecting Okinawa on Sunday morning. A weather station at Kadena Air Force Base (RODN) was reporting a sustained wind speed of 25 m.p.h. (40 km/h) and a wind gusts of 35 m.p.h. (55 km/h) even though the center of Jangmi was 255 miles (410 km) south of the station.
Typhoon Jangmi continued to intensify slowly during Saturday night. A very large circular eye was at the center of Typhoon Jangmi. The eye had a diameter of 80 miles (130 km). The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the center Jangmi’s circulation. Storms near the center of Jangmi generated upper level divergence that pumped mass away from the typhoon. The removal of mass caused the surface pressure to decrease.
The circulation around Typhoon Jangmi was large. Winds to typhoon force extended out 90 miles (145 km) from the center of Jangmi’s circulation. Winds to tropical storm force extended out 230 miles (370 km) from the center of Typhoon Jangmi.
The Hurricane Intensity Index (HII) for Typhoon Jangmi was 12.7. The Hurricane Size Index (HSI) was 29.7 and the Hurricane Wind Intensity Size Index (HWISI) was 42.4.
Typhoon Jangmi will move into an environment that will become unfavorable for intensification during the next 24 hours. Jangmi will move over water where the Sea Surface Temperatures are near 26°C. It will move under the eastern part of an upper level trough that is over the east coast of China. The upper level trough will produce southwesterly winds that will blow toward the top of Jangmi’s circulation. Those winds will cause the vertical wind shear to increase. Typhoon Jangmi will start to weaken slowly when the vertical wind shear increases.
Typhoon 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 north during the next 24 hours. On its anticipated track, the center of Typhoon Jangmi will reach Okinawa in 18 hours.
Typhoon Jangmi will bring strong winds and locally heavy rain to the Ryukyu Islands including Okinawa. Heavy rain is could cause flash floods in some locations. Typhoon Jangmi could also cause a storm surge of up to 10 feet (3 meters) along portions of the coasts of the Ryukyu Islands.