Tropical Storm Haikui Moves Across South China Sea

Tropical Storm Haikui moved across the South China Sea on Friday.  At 10:00 p.m. EST on Friday the center of Tropical Storm Haikui was located at latitude 17.8°N and longitude 115.4°E which put it about 485 miles (785 km) east of Da Nang, Vietnam.  Haikui was moving toward the west-northwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 994 mb.

Tropical Storm Haikui strengthened slightly on Friday, but the circulation remained asymmetrical.  Most of the stronger thunderstorms were occurring east of the center of circulation.  A short primary rainband wrapped around the eastern side of the center.  Several other broken bands of showers and thunderstorms formed to the east of the primary rainband.  Bands of showers and storms were also located south of the center of circulation.  Storms near the core of Tropical Storm Haikui were generating some upper level divergence which was pumping mass away to the east of the tropical storm.  The bands in the western half of the circulation consisted primarily of low clouds and showers.

Tropical Storm Haikui will move through an environment marginally favorable for intensification during the next 24 to 36 hours.  Haikui will move over water where the Sea Surface Temperature is near 29°C.  Colder, drier air over eastern Asia was flowing toward the western side of Tropical Storm Haikui.  The upper level westerly winds of the middle latitudes were blowing just to the northwest of Tropical Storm Haikui.  Those winds were causing moderate vertical shear over the northwestern periphery of Haikui.  The winds over the core of Tropical Storm Haikui were weaker.  If Tropical Storm Haikui remains south of the stronger westerly winds, it could intensify a little more during the next 24 hours.

A ridge to the north of Haikui is steering the tropical storm toward the west-northwest.  The ridge is forecast to strengthen and Tropical Storm Haikui is likely to move more toward the west during the next several days.  On its anticipated track Tropical Storm Haikui will pass south of Hainan Island in about 48 hours.  Tropical Storm Haikui could reach the coast of Vietnam in less than three days.