Tropical Storm Wipha formed south of Macau late on Tuesday.  At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Wipha was located at latitude 18.8°N and longitude 112.6°E which put it about 175 miles (285 km) south of Macau.  Wipha was moving toward the 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 994 mb.

The circulation around Tropical Storm Wipha was large, but Wipha did not have a well formed inner core.  Winds to tropical storm force extended out about 200 miles (320 km) from the center of circulation.  However, there were no strong thunderstorms near the center.  Stronger thunderstorms were occurring in bands well to the south and east of the center of circulation.  Bands northwest of the center consisted primarily of showers and lower clouds.

The large lower level circulation of Tropical Storm Wipha was just to the southeast of an upper low over the northwestern part of the South China Sea.  The upper low was circulating some drier air over the northwestern part of Wipha.  It was also causing some vertical wind shear.  The drier air and wind shear were inhibiting the formation of thunderstorms in the northwestern part of Tropical Storm Wipha.

Tropical Storm Wipha will move through an environment somewhat favorable for intensification during the next 24 hours.  Wipha will move over water where the Sea Surface Temperature is near 30°C.  The upper low will continue to inhibit the strengthening of Tropical Storm Wipha.  If thunderstorms begin to develop near the center of Wipha, then the tropical storm could strengthen.

Tropical Storm Wipha will move around the southwestern part of a subtropical ridge over the Western North Pacific Ocean.  The ridge will steer Wipha toward the northwest during the next 24 hours.  On its anticipated track the center of Tropical Storm Wipha will be near the northern part of Hainan Island and the south coast of China in 18 to 24 hours.  Wipha could move more toward the west when it reaches the Gulf of Tongking.  Although Tropical Storm Wipha will bring gusty winds to southern China and northern Vietnam, locally heavy rain and the potential for floods will be greater risks.