Typhoon Khanun Approaches Okinawa

Typhoon Khanun was approaching Okinawa on Monday night. At 11:00 p.m. EDT on Monday the center of Typhoon Khanun was located at latitude 24.8°N and longitude 129.1°E which put it about 165 miles (265 km) southeast of Okinawa. Khanun was moving toward the west-northwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 140 m.p.h. (225 km/h) and there were wind gusts to 165 m.p.h. (265 km/h). The minimum surface pressure was 930 mb.

Typhoon Khanun continued to strengthen on Monday. A circular eye with a diameter of 30 miles (50 km) was at the center of Khanun’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 Khanun. Storms near the core generated strong upper level divergence that pumped mass away form the typhoon in all directions.

The core of Typhoon Khanun contracted on Monday as Khanun intensified. Winds to typhoon force extended out 50 miles (80 km) from the center of Khanun’s circulation. Winds to tropical storm force extended out 265 miles (425 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Khanun was 28.3. The Hurricane Size Index (HSI) was 17.4 and the Hurricane Wind Intensity Size Index (HWISI) was 45.7. Khanun is capable of causing regional severe damage. Typhoon Khanun was almost as strong as Hurricane Ida was when Ida hit Louisiana in 2021. Khanun was larger than Ida was.

Typhoon Khanun will move through an environment that will be favorable for a strong typhoon during the next 24 hours. Khanun 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 Khanun could intensify during the next 24 hours unless an eyewall replacement cycle occurs. If the inner end of a rainband wraps around the existing eye and eyewall, then concentric eyewalls could develop. The formation of concentric eyewalls would cause Khanun to weaken.

Typhoon Khanun will move around the southwestern side of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Khanun toward the west-northwest during the next 24 hours. On its anticipated track, the core of Typhoon Khanun will be just south of Okinawa in 12 hours. Khanun will bring strong, gusty winds and locally heavy rain to Okinawa and the other southern Ryukyu Islands. Heavy rain will cause flash floods in some locations. Typhoon Khanun will also cause a significant storms surge in the parts of islands where the winds blow water toward the coast.