Typhoon Cempaka was speeding toward the east-northeast over the Western North Pacific Ocean east of Japan on Wednesday.  At 4:00 a.m. EST on Wednesday the center of Typhoon Cempaka was located at latitude 29.6°N and longitude 151.9°E which put the center about 410 miles (665 km) northwest of Minami Tori Shima.  Cempaka was moving toward the east-northeast at 38 m.p.h. (61 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 983 mb.

Typhoon Cempaka was making a transition to a strong extratropical cyclone on Wednesday morning.  Thunderstorms were still occurring in bands in the eastern side of Cempaka’s circulation.  Bands in the western side of Typhoon Cempaka consisted primarily of showers and lower clouds.  Storms near the center of Cempaka generated some upper level divergence that pumped mass away to the northeast of the typhoon.  The removal of mass in the upper levels was less than the convergence of mass in the lower levels of the atmosphere.  So, the surface pressure was increasing on Wednesday.

The transition to an extratropical cyclone was having other effects on the structure of Typhoon Cempaka.  A cold front extended to the south of the center of Cempaka’s circulation.  A warm front extended to the northeast of Typhoon Cempaka.

The transition to an extra tropical cyclone was also having an effect on the distribution of wind speeds in Typhoon Cempaka.  Winds to typhoon force extended out 35 miles (55 km) from the center of Cempaka’s circulation.  Winds to tropical storm force extended out 120 miles (195 km) from the center of Typhoon Cempaka.

Typhoon Cempaka will move through an environment that will be unfavorable for intensification of a typhoon during the next 24 hours.  Cempaka will move over water where the Sea Surface Temperatures are near 23°C.  It will move under the eastern part of an upper level trough that is east of Japan.  The upper level trough will produce strong southwesterly winds that will blow toward the top of Cempaka’s circulation.  Those winds will cause strong vertical wind shear.  The strong vertical wind shear and the cooler Sea Surface Temperatures will cause Typhoon Cempaka to complete the transition to a strong extratropical cyclone during the next 24 hours.

The upper level trough over Japan will steer Typhoon Cempaka quickly toward the east-northeast during the next 24 hours.  On its anticipated track, Typhoon Cempaka will move farther away from Japan.