Typhoon Choi-wan intensified to the equivalent of a major hurricane as it moved east-southeast of Iwo To on Saturday. At 11:00 p.m. EDT on Saturday the center of Typhoon Choi-wan was located at latitude 22.5°N and longitude 147.1°E which put the center about 410 miles (665 km) east-southeast of Iwo To. Choi-wan was moving toward the north-northeast at 16 m.p.h. (26 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 942 mb.
Typhoon Choi-wan intensified to the equivalent of a major hurricane on Saturday. A circular eye with a diameter of 20 miles (32 km) was at the center of Choi-wan’s circulation. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Typhoon Choi-wan. Storms near the core of Choi-wan 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 Choi-wan was large. Winds to typhoon force extended out 90 miles (145 km) from the center of Choi-wan’s circulation. Winds to tropical storm force extended out 355 miles (575 km) from the center of Typhoon Choi-wan.
The Hurricane Intensity Index (HII) for Typhoon Choi-wan is 23.6. The Hurricane Size Index (HSI) is 28.8 and the Hurricane Wind Intensity Size Index (HWISI) is 52.4. Typhoon Choi-wan is similar in size and intensity to Hurricane Wilma when Wilma hit South Florida in 2005.
Typhoon Choi-wan will move through an environment that will be favorable for intensification during the next 24 hours. Choi-wan Choi-wan will move over water where the Sea Surface Temperatures are near 28°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Typhoon Choi-wan is likely to continue to intensify during the next 24 hours unless an eyewall replacement cycle occurs.
Typhoon Choi-wan 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 Choi-wan toward the north during the next 24 hours. On its anticipated track, the center of Typhoon Choi-wan will pass east of Iwo To on Sunday.