Typhoon Khanun Stalls West of Okinawa

Typhoon Khanun stalled over the Western North Pacific Ocean west of Okinawa on Thursday. At 11:00 p.m. EDT on Thursday the center of Typhoon Khanun was located at latitude 27.1°N and longitude 124.8°E which put it about 200 miles (325 km) west of Okinawa. Khanun was moving toward the northeast at 4 m.p.h. (6 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 970 mb.

Typhoon Khanun weakened while it stalled west of Okinawa. Khanun had almost completed an eyewall replacement cyclone on Thursday night. The former inner eyewalll consisted of a ring of low clouds and showers. The strongest winds were occurring in the southern part of the ring of showers. A very large, broken outer eyewall with a diameter of 150 miles (240 km) surrounded the center of Typhoon Khanun. Bands of showers and thunderstorms were revolving around the outer eyewall. Storms around the outer eyewall generated upper level divergence that pumped mass away from the typhoon.

The circulation around Typhoon Khanun was large, even though Khanun was weaker. Winds to typhoon force extended out 50 miles (80 km) to the south of the center of Khanun. Winds to tropical storm force extended out 190 miles (305 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Khanun was 10.4. The Hurricane Size Index (HSI) was 14.7 and the Hurricane Wind Intensity Size Index (HWISI) was 25.1. Typhoon Khanun was capable of causing regional minor damage.

Typhoon Khanun will move through an environment that will be favorable for intensification during the next 24 hours. Khanun 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. However, Typhoon Khanun is unlikely to intensify during the next 24 hours, because of the almost completed eyewall replacement cycle. The eyewall replacement cycle disrupted the inner core of Khanun. Typhoon Khanun is unlikely to intensify until the larger outer eyewall begins to contract closer to the center of circulation. Khanun could actually weaken a little more on Friday.

Typhoon Khanun will move around the northwestern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Khanun toward the east-northeast during the next 24 hours. On its anticipated track, Typhoon Khanun will move back toward the Ryukyu Islands during the next 24 hours. Typhoon Khanun will to produce strong, gusty winds and locally heavy rain in Okinawa and the other northern Ryukyu Islands. Heavy rain will cause flash floods in some locations. The center of Khanun could be just north of Okinawa in 36 hours.