Typhoon Nanmadol rapidly intensified to the equivalent of a major hurricane south of Japan during Thursday night. At 11:00 p.m. EDT on Thursday the center of Typhoon Nanmadol was located at latitude 24.1°N and longitude 135.4°E which put it about 535 miles (860 km) east-southeast of Okinawa. Nanmadol was moving toward the northwest at 8 m.p.h. (13 km/h). The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 155 m.p.h. (250 km/h). The minimum surface pressure was 947 mb.

Typhoon Nanmadol rapidly intensified to the equivalent of a major hurricane over the Western North Pacific Ocean south of Japan during Thursday night. A well formed circular eye was present 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 strong upper level divergence that pumped mass away from the typhoon in all directions.

The circulation around Typhoon Nanmadol was symmetrical. Winds to typhoon force extended out 60 miles (95 km) from the center of Nanmadol. Winds to tropical storm force extended out 200 miles (320 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Nanmadol was 23.6. The Hurricane Size Index (HSI) was 20.6 and the Hurricane Wind Intensity Size Index (HWISI) was 44.2. Typhoon Nanmadol was capable of causing widespread major damage.

Typhoon Nanmadol will move through an environment favorable for intensification during the next 24 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 24 hours. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could form. That would be the start of an eyewall replacement cycle that would cause Nanmadol to weaken.

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 the center of Typhoon Nanmadol will be east of Minami Daito Jima within 24 hours. Nanmadol could be east of Amami Oshima in 36 hours. Typhoon Nanmadol will bring strong, gusty winds and heavy rain to parts of the northern Ryukyu Islands during the weekend.

Elsewhere over the Western North Pacific Ocean, Tropical Storm Muifa weakened over the northern Yellow Sea. At 11:00 p.m. EDT on Thursday the center of Tropical Storm Muifa was located at latitude 38.5°N and longitude 121.8°E which put it about 50 miles (80 km) northeast of Yantai, China. Muifa was moving toward the north-northeast at 16 m.p.h. (26 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.