Tropical Storm Trases developed over the East China Sea south of Jeju Island, South Korea on Sunday afternoon. At 2:00 p.m. EDT on Sunday the center of Tropical Storm Trases was located at latitude 30.1°N and longitude 126.3°E which put it about 175 miles (280 km) south of Jeju Island, South Korea. Trases was moving toward the north-northwest at 18 m.p.h. (29 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 998 mb.
The circulation at the center of a large low pressure system over the East China Sea strengthened on Sunday afternoon and the Japan Meteorological Agency designated the system as Tropical Storm Trases. The distribution of thunderstorms around Tropical Storm Trases was asymmetrical. Thunderstorms were occurring in bands in the southern part of Trases’ circulation. Bands in the other part of the tropical storm consisted primarily of showers and lower clouds. The air in the northern part of Tropical Storm Trases was cooler and drier. The cooler, drier air was inhibiting the formation of thunderstorms in that part of Trases.
Tropical Storm Trases will move through an environment marginally favorable for intensification during the next 12 hours. Trases will will move over water where the Sea Surface Temperatures are near 26˚C. It will move under the axis of an upper level ridge centered north of Japan. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. However, the cooler drier air on the northern side of Trases will limit the potential for intensification. Tropical Storm Trases could intensify a little during the next 12 hours. Trases will move over cooler water on Monday and it is likely to weaken at that time.
Tropical storm Trases will move around the western side of a high pressure system over the Western North Pacific Ocean. The high pressure system will steer Trases toward the north during the next 24 hours. On its anticipated track the center of Tropical Storm Trases could reach Jeju Island within 12 hours. Trases could make landfall on the west coast of South Korea on Monday. Tropical Storm Trases will bring gusty winds and locally heavy rain to parts of South Korea.