Powerful Typhoon Hinnamnor headed toward South Korea on Sunday night. At 11:00 p.m. EDT on Sunday the center of Typhoon Hinnamnor was located at latitude 30.5°N and longitude 125.3°E which put it about 440 miles (710 km) southwest of Busan, South Korea. Hinnamnor was moving toward the north at 14 m.p.h. (22 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 Hinnamnor was a large and dangerous storm as it headed toward South Korea on Sunday night. Winds to typhoon force extended out 80 miles (130 km) from the center of Hinnamnor’s circulation. Winds to tropical storm force extended out 260 miles (420 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 23.6. The Hurricane Size Index (HSI) was 29.4 and the Hurricane Wind Intensity Size Index (HWISI) was 53.0. Typhoon Hinnamnor was capable of causing widespread major damage.

The circulation around Typhoon Hinnamnor was very well organized. A small eye with a diameter of 12 miles (19 km) was at the center of Hinnamnor’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 Hinnamnor. Storms near the core generated upper level divergence that pumped mass away from the typhoon.

Typhoon Hinnamnor will move into an environment less favorable for a strong typhoon during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 28˚C. An upper level trough over China will produce southwesterly winds that will blow toward the top of Hinnamnor’s circulation. Those winds will cause the vertical wind shear to increase during the next 24 hours. Typhoon Hinnamnor will start to weaken when the wind shear increases.

The upper level trough over China will steer Typhoon Hinnamnor toward the northeast during the next 24 hours. On its anticipated track, the center of Typhoon Hinnamnor will be near Jeju Island in 12 hours. Hinnamnor will approach the coast of South Korea near Busan in 18 hours. Although Typhoon Hinnamnor will weaken as it approaches South Korea, it will still be a large, powerful typhoon. Hinnamnor will bring strong gusty winds and locally heavy rain to South Korea. Heavy rain could cause flash floods in some locations. Typhoon Hinnamnor could also bring gusty winds and locally heavy rain to parts of Japan.