Tropical Storm Wukong formed southeast of Japan on Monday. At 5:00 p.m. EDT on Monday the center of Tropical Storm Wukong was located at latitude 29.0°N and longitude 159.0°E which put it about 1370 miles (2210 km) east-southeast of Tokyo, Japan. Wukong was moving toward the north at 24 m.p.h. (39 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and the were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 984 mb.
A cluster of thunderstorms developed southeast of Japan during the weekend and a low level center of circulation formed near the southwestern edge of the cluster of storms. However, strong upper level winds blowing from the southwest kept blowing the top of the circulation northeast of the low level center and the system was unable to develop. The upper level winds slowed on Monday and a band of showers and thunderstorms wrapped around the northern and western sides of the center of circulation. The Japan Meteorological Agency designated the system as Tropical Storm Wukong.
The circulation of Tropical Storm Wukong organized quickly after the upper level winds weakened. As mentioned above, a primary rainband wrapped around the northern and western sides of the center of circulation. Storms in the primary rainband generated upper level divergence which was pumping mass away to the north of the tropical storm. Several other bands of showers and thunderstorms developed in the eastern half of the circulation. Bands south and west of the center consisted primarily of showers and lower clouds.
Tropical Storm Wukong will move through an environment favorable for intensification during the next day or so. Wukong will move over water where the Sea Surface Temperature is near 27°C. Wukong is moving along the eastern portion of an upper level trough. The trough is producing southwesterly winds which are blowing toward the top of the circulation. However, those winds weakened on Monday and they will not cause enough vertical wind shear to prevent further intensification. Tropical Storm Wukong could strengthen into a typhoon during the next 24 to 36 hours. Eventually, Wukong will move over cooler water and it will begin to weaken.
Tropical Storm Wukong is moving between an upper level trough to the west and an upper level ridge to the east. The trough and ridge were combining to steer Wukong toward the north and a general northerly motion is expected to continue. On its anticipated track Tropical Storm Wukong will stay west of the larger islands of Japan. Wukong could approach the Kuril Islands in about three days.
Elsewhere over the Western North Pacific former Tropical Storm Ampil weakened to a tropical depression over land southeast of Beijing, China, Tropical Storm Son-tinh meandered near the coast of southeastern China and Tropical Depression 15W organized southwest of Iwo To, Japan. At 5:00 p.m. EDT on Monday the center of Tropical Depression Ampil was located at latitude 38.8°N and longitude 117.6°E which put it about 110 miles (175 km) southeast of Beijing, China. Ampil was moving toward the north-northwest at 18 m.p.h. (29 km/h). The maximum sustained wind speed was 35 m.p.h. (55k km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 998 mb. Tropical Depression Ampil was still dropping locally heavy rain over parts of eastern China.
At 5:00 p.m. EDT on Monday the center of Tropical Storm Son-tinh was located at latitude 21.2°N and longitude 109.0°E which put it about 40 miles (65 km) southeast of Beihai, China. Son-tinh was moving toward the west-northwest at 6 m.p.h. (10 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 996 mb. Tropical Storm Son-tinh was dropping locally heavy rain over parts of southeastern China and Hainan Island.
At 5:00 p.m. EDT on Monday the center of Tropical Depression 15W was located at latitude 17.6°N and longitude 136.3°E which put it about 585 miles (945 km) southwest of Iwo To, Japan. It was moving toward the north-northwest at 10 m.p.h. (16 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 998 mb. The circulation of Tropical Depression 15W became more organized on Monday and it could eventually strengthen into a typhoon when it moves toward Iwo To later this week.