Former Tropical Storm Nanmadol strengthened to a typhoon south of Japan on Thursday morning. At 5:00 a.m. EDT on Thursday the center of Typhoon Nanmadol was located at latitude 23.6°N and longitude 137.5°E which put it about 660 miles (1065 km) east-southeast of Okinawa. Nanmadol was moving toward the west-northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 981 mb.

Former Tropical Storm Nanmadol intensified to a typhoon over the Western North Pacific Ocean south of Japan on Thursday morning. A circular eye formed at the center of Nanmadol’s circulation. The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Nanmadol. Storms near the core generated upper level divergence that pumped mass away from the typhoon. Winds to typhoon force extended out 30 miles (50 km) from the center of circulation in the northern side of Nanmadol. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation.

Typhoon Nanmadol will move through an environment favorable for intensification during the next 36 hours. Nanmadol will move over water where the Sea Surface Temperatures are near 29˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Nanmadol will intensify during the next 36 hours. It is likely to strengthen to the equivalent of a major hurricane.

Typhoon Nanmadol will move around the southwestern part of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Nanmadol toward then northwest during the next 36 hours. On its anticipated track Typhoon Nanmadol could approach the northern Ryukyu Islands in 48 hours. Nanmadol is likely to be a large, dangerous typhoon when it moves near the north Ryukyu Islands.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Muifa weakened over the Yellow Sea and Typhoon Merbok was transitioning to a powerful extratropical cyclone south of the western Aleutian Islands. At 5:00 a.m. EDT on Thursday the center of Tropical Storm Muifa was located at latitude 34.6°N and longitude 120.3°E which put it about 100 miles (160 km) south-southwest of Qingdao, China. Muifa was moving toward the north-northwest at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 994 mb.

At 5:00 a.m. EDT on Thursday the center of Typhoon Merbok was located at latitude 41.0°N and longitude 166.0°E which put it about 890 miles (1435 km) south-southwest of Kiska, Alaska. Merbok was moving toward the north-northeast at 45 m.p.h. (75 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 960 mb.