Tropical Storm Namtheun Spins Southeast of Japan

Tropical Storm Namtheun was spinning southeast of Japan on Friday morning. At 5:00 a.m. EDT on Friday the center of Tropical Storm Namtheun was located at latitude 26.6°N and longitude 161.9°E which put it about 495 miles (800 km) east-northeast of Minami Tori Shima. Namtheun was moving toward the east-northeast at 18 m.p.h. (29 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 994 mb.

Tropical Storm Namtheun was the only current tropical cyclone on Friday morning as it churned over the Western North Pacific Ocean between Japan and Hawaii. Namtheun intensified during the past 24 hours as it moved well to the east of the main islands of Japan. The inner end of a rainband wrapped around the center of Tropical Storm Namtheun. A broken ring of thunderstorms was around the center of circulation. The strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Namtheun. Storms near the core generated upper level divergence that pumped mass away from the tropical storm. Winds to tropical storm force extended out 85 miles (135 km) from the center of circulation.

Tropical Storm Namtheun will move through an environment somewhat favorable for intensification during the next 24 hours. Namtheun will move over water where the Sea Surface Temperatures are near 27˚C. An upper level trough southeast of Japan will produce southwesterly winds that will blow toward the top of Namtheun’s circulation. Those winds will cause some vertical wind shear and the wind shear will inhibit intensification. Tropical Storm Namtheun could strengthen during the next 24 hours. Namtheun will move over colder water during the weekend. It will also move in a region where the upper level winds will be stronger. Tropical Storm Namtheun will weaken during the weekend.

The upper level trough southeast of Japan will steer Tropical Storm Namtheun toward the northeast during the next several days. On its anticipated track Namtheun will move farther away from Japan.