Typhoon Namtheun spun up quickly on Thursday and moved steadily toward Kyushu in southern Japan. At 11:00 p.m. EDT on Thursday the center of Typhoon Namtheun was located at latitude 26.6°N and longitude 130.8°E which put it about 335 miles (540 km) south of Kagoshima, Japan. Namtheun was moving toward the north at 7 m.p.h. (11 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 975 mb.
Typhoon Namtheun developed quickly from a low pressure system along a surface trough. Namtheun has a small but very well organized circulation. It has a tiny pinhole eye surrounded by a ring of strong thunderstorms. Several other rainbands are spiraling around the ring of strong thunderstorms. The thunderstorms are generating upper level divergence which is pumping out mass in all directions. The upper level divergence is slightly less to the west of the center of circulation.
Typhoon Namtheun is in an environment favorable for intensification. It is moving over water where the Sea Surface Temperature is near 30°C. Although there is a large upper level trough over eastern Asia which contains strong southwesterly winds, Typhoon Namtheun developed east of those strong winds. It is in an area where the upper level winds are weaker and there is little vertical wind shear. Namtheun is likely to intensify more during the next day or two. However, Namtheun’s small circulation means that it will respond very rapidly to positive or negative changes in its surrounding environment.
A ridge to the east of Namtheun is steering the typhoon toward the north and that general motion is expected to continue for several more days. On its anticipated track Typhoon Namtheun could be very near the southern tip of Kyushu within 48 hours. It could bring strong winds and heavy rain to parts of southern Japan.