Tropical Storm Koto meandered over the South China Sea east of Vietnam on Friday. At 4:00 p.m. EST on Friday the center of Tropical Storm Koto was located at latitude 13.0°N and longitude 112.5°E which put the center about 235 miles (380 km) east-northeast of Nha Trang, Vietnam. Koto was moving toward the north at 3 m.p.h. (5 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 993 mb.
Tropical Storm Koto was maintaining its intensity on Friday. New thunderstorms develop west of the center of Koto’s circulation. Bands in the other parts of Tropical Storm Koto consisted primarily of showers and lower clouds. Storms west of the center of Koto generated some upper level divergence that pumped mass away to the northwest of the tropical storm. The removal of mass in the upper levels was nearly equal to the inflow of mass in the lower levels of the atmosphere. So, the surface pressure was nearly steady.
The distribution of wind speeds around Tropical Storm Koto continued to be very asymmetrical. Winds to tropical storm force extended out 180 miles (290 km) in the western side of Koto’s circulation. Winds to tropical storm force extended out 65 miles (105 km) in the eastern side of Tropical Storm Koto.
Tropical Storm Koto will be in an environment that will be unfavorable for intensification during the next 24 hours. Koto will move over water where the Sea Surface Temperatures are near 29°C. It will move under the southern part of an upper level ridge that is over the South China Sea. The upper level ridge will produce southeasterly winds that will blow toward the top of Koto’s circulation. Those winds will cause moderate vertical wind shear. In addition, Tropical Storm Koto will continue to move through the region of drier air that is over the South China Sea. Tropical Storm Koto in likely to maintain its intensity during the next 24 hours because of the moderate vertical wind shear and the effects of the drier air.
Tropical Storm Koto will continue to be in a region where the steering currents are weak during the next 24 hours. On its anticipated track, Tropical Storm Koto will meander slowly over the South China Sea on Friday.
Elsewhere, Tropical Cyclone Senyar moved across Malaysia and over the extreme southwestern part of the Western North Pacific Ocean. Both the U.S. Joint Typhoon Warning Center and the Japan Meteorological Agency were classifying Senyar as a tropical depression. At 4:00 p.m. EST on Friday the center of Tropical Depression Senyar was located at latitude 4.8°N and longitude 105.5°E which put the center about 160 miles (260 km) east-northeast of Kuantan, Malaysia. Senyar was moving toward the east-northeast at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1003 mb.