China: Tropical Depression 4 tracking west-northwestward over the South China Sea early July 20

Tropical Depression 4 is tracking west-northwestward over the South China Sea early July 20. As of 11:00 CST, the system's center of circulation is approximately 643 km (399 miles) east of Da Nang, Vietnam.

Forecast models indicate that the weather system will strengthen into a tropical storm as it passes over the Paracel Islands. The storm is forecast to strengthen further but remain at tropical storm strength as it turns to track northwestward and makes landfall over Hainan Province, China, late July 21 before weakening into a tropical depression and making another landfall over Guangxi Province early July 23. After landfall, the storm is likely to weaken rapidly as it turns to track northwards and dissipates over southern Guangxi Province early July 24. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

The China Meteorological Administration has issued a blue rainstorm warning (the lowest level on a four-tier scale) across south-central Guangdong and eastern and southern Hainan provinces and a blue severe convective weather warning for eastern Hainan Province. Authorities will likely issue new alerts or update/rescind existing advisories as the storm approaches.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. If weather conditions prove hazardous, localized evacuations, flash flooding, and landslides are possible.

Inclement weather could trigger localized business, transport, and utility disruptions, rendering some bridges or roadways impassable. Flight disruptions at airports and temporary port closures are also possible. Stagnant pools of water during and after flooding increase insect- and waterborne diseases, such as dengue fever, cholera, and malaria. Exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.