Former Tropical Storm Hinnamnor rapidly intensified to a typhoon near Chichi Jima on Monday morning. At 5:00 a.m. EDT on Monday the center of Typhoon Hinnamnor was located at latitude 27.4°N and longitude 142.2°E which put it about 30 miles (50 km) north of Chichi Jima. Hinnamnor was moving toward the west at 22 m.p.h. (35 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 967 mb.

Former Tropical Storm Hinnamnor rapidly intensified to a typhoon in a favorable environment over the Western North Pacific Ocean near Chichi Jima. A small circular eye formed 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.

The circulation around Typhoon Hinnamnor was small. Winds to typhoon force extended out 25 miles (40 km) from the center of Hinnamnor. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Hinnamnor was 12.7. The Hurricane Size Index (HSI) was 7.8 and the Hurricane Wind Intensity Size Index (HWISI) was 20.5.

Typhoon Hinnamnor will move through an area favorable for intensification during the next 24 hours. Hinnamnor will move over water where the Sea Surface Temperatures are 30˚C. It will move through region where the winds at all levels of the troposphere are blowing from the east. Since the winds at different levels are blowing from the same direction, there will be little vertical wind shear. Typhoon Hinnamnor is likely to continue to intensify rapidly during the next 24 hours. Hinnamnor could strengthen to the equivalent of a major hurricane.

Typhoon Hinnamnor will move around the southwestern part of a high pressure system that extends over Japan. The high pressure system will steer Hinnamnor toward the west during the 48 hours. On its anticipated track Typhoon Hinnamnor could approach the Ryukyu Islands in 48 hours. Hinnamnor will continue to produce strong gusty winds and locally heavy rain on Chichi Jima during the next few hours until it moves farther away. Typhoon Hinnamnor could be the equivalent of a major hurricane when it approaches the Ryukyu Islands.