South China Sea: Tropical Depression 4 forms in the eastern South China Sea, tracking westward late July 14

Event

Tropical Depression 4, known in the Philippines as Dodong, has formed in the eastern South China Sea and is tracking westward late July 14. As of 20:00 PHST, the system's center of circulation was approximately 332 km (206 miles) northwest of Manila, Philippines.

Forecast models indicate that the system will strengthen into a tropical storm as it tracks northwestward over the eastern South China Sea away from the Philippines July 14-16. The storm is then forecast to strengthen into a typhoon as it turns to track west-northwestward over the northern South China Sea July 16-17, before making landfall over the Leizhou Peninsula in far southwestern Guangdong Province, China, early July 18. The system is expected to weaken back to tropical storm strength as it moves over the Leizhou Peninsula and the Gulf of Tonkin July 18, before making a second landfall over far northeastern Vietnam late July 18. The storm is likely to weaken into a tropical depression and dissipate over northern Vietnam July 19. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

As of late July 14, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) has issued a tropical cyclone wind signal no. 1 (the lowest level on a five-tier scale) for parts of Abra, Apayao, western Cagayan, Ilocos Norte, Ilocos Sur, Kalinga, and Mountain provinces. Rainfall totals of 5-10 cm (2-4 inches) are expected in parts of the northwestern Philippines through July 15. Vietnam's National Centre for Hydro-Meteorological Forecasting has not issued any warnings for land areas as of July 14; however, the center has warned of strong winds and large waves in northeastern seas and along the northeast coast. The China Meteorological Administration has also yet to issue any warnings for the storm system.

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.

The inclement weather could trigger localized business, transport, and utility disruptions and render some bridges or roadways impassable. Flight disruptions at regional airports and temporary closures of ports are also possible. Exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.

Advice

Activate contingency plans in areas where officials forecast typhoon or tropical storm conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents and necessary medications in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks.

Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.

Resources

Joint Typhoon Warning Center
China Meteorological Administration
Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA)
Vietnam National Centre for Hydro-Meteorological Forecasting (NCHMF)