Tropical Storm Choi-wan moved toward Taiwan on Thursday. At 5:00 p.m. EDT on Thursday the center of Tropical Storm Choi-wan was located at latitude 20.0°N and longitude 118.9°E which put it about 185 miles (300 km) south-southwest of Taiwan. Choi-wan was moving toward the north-northeast at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1002 mb.
Tropical Storm Choi-wan turned toward the north-northeast on Thursday which put it on a track towards southern Taiwan. The distribution of thunderstorms around Choi-wan was asymmetrical. The strongest thunderstorms were occurring in bands in the southwestern quadrant of Tropical Storm Choi-wan. Bands in the other quadrants of Choi-wan consisted primarily of showers and lower clouds. The distribution of wind speeds around Tropical Storm Choi-wan was also asymmetrical. Winds to tropical storm force extended out 125 miles (200 km) on the western side of Choi-wan. Winds to tropical storm force only extended out 65 miles (105 km) on the eastern side of the circulation.
Tropical Storm Choi-wan will move through an area that is mostly unfavorable for intensification during the next 36 hours. The center of Choi-wan will move over an area where the Sea Surface Temperatures are near 30°C. However, an upper level ridge centered over southern China will produce moderate northeasterly winds that will blow toward the top of the tropical storm. Those winds will cause moderate vertical wind shear and they are already responsible for the asymmetrical distribution of thunderstorms. The moderate vertical wind shear will likely prevent intensification of Tropical Storm Choi-wan.
Tropical Storm Choi-wan will move around the northwestern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Choi-wan toward the north-northeast during the next 24 hours. On its anticipated track the center of Tropical Storm Choi-wan will reach southern Taiwan in 12 hours. Choi-wan could drop locally heavy rain over parts of southern Taiwan. Flash floods could occur in some locations. Tropical Storm Choi-wan could approach the southern Ryuku Islands in 24 hours. Choi-wan could bring a period of gusty winds to southern Taiwan and the southern Ryukyu Islands.