Typhoon Cempaka started to move eastward over the Western North Pacific Ocean on Monday. At 10:00 p.m. EST on Monday the center of Typhoon Cempaka was located at latitude 25.3°N and longitude 139.0°E which put the center about 205 miles (335 km) west of Iwo To. Cempaka was moving toward the east-northeast at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h). The minimum surface pressure was 964 mb.
Typhoon Cempaka strengthened earlier on Monday, but Cempaka was showing signs of weakening on Monday evening. A small circular eye was still visible at the center of Cempaka’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 center of Typhoon Cempaka. Storms near the center of Cempaka generated upper level divergence that pumped mass away from the typhoon. The removal of mass caused the surface pressure to decrease on Monday.
The circulation around Typhoon Cempaka was small. Winds to typhoon force extended out 40 miles (65 km) from the center of Cempaka’s circulation. Winds to tropical storm force extended out 90 miles (145 km) from the center of Typhoon Cempaka.
The Hurricane Intensity Index (HII) for Typhoon Cempaka is 19.2. The Hurricane Size Index (HSI) is 13.0 and the Hurricane Wind intensity Size Index (HWISI) is 32.2. Typhoon Cempaka is similar in size and intensity to Hurricane Sally when Sally hit Alabama in 2020.
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 26°C. It will move under the eastern part of an upper level trough that is over Japan. The upper level trough will produce southwesterly winds that will blow toward the top of Cempaka’s circulation. Those winds will cause moderate vertical wind shear. The moderate vertical wind shear and the cooler Sea Surface Temperatures will cause Typhoon Cempaka to weaken during the next 24 hours. The vertical wind shear and cooler water will also cause Cempaka to begin to make a transition to a strong extratropical cyclone.
The upper level trough over Japan will steer Typhoon Cempaka toward the east-northeast during the next 24 hours. On its anticipated track, Typhoon Cempaka will pass just north of Iwo To on Tuesday.
Typhoon Cempaka will bring strong winds and heavy rain to Iwo To and the southern Ogasawara Islands.