South China Sea: Tropical Storm Sanba tracking northwestward off the coast of Hainan Island, China, as of late Oct. 18 /update 2

Event

Tropical Storm Sanba is tracking northwestward across the South China Sea, off the west coast of Hainan Island, China, late Oct. 18. As of 19:00 ICT, the system's center of circulation was approximately 289 km (180 miles) north of Da Nang.

Forecast models indicate that the storm will strengthen slightly as it tracks generally north-northwestward past Hainan and across the Gulf of Tonkin late Oct. 18-Oct. 19. The system is then forecast to make an abrupt u-turn as it approaches the northeastern Vietnam coast around Quang Ninh province early Oct. 20, and will weaken into a tropical depression and then dissipate as it tracks southwestward over the Gulf of Tonkin Sept. 20-21. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

Vietnam's National Center for Hydrometeorological Forecasting (NCHMF) has issued a warning bulletin for the storm system, advising that heavy to very heavy rainfall is likely from Quang Tri to Quang Nam provinces from late Oct. 19. Moderate rainfall is also likely in other coastal regions and north-central, northeastern, and southern parts of the country from late Oct. 19. Rough seas and strong winds are also expected over coastal waters off northern and central Vietnam.

The China Meteorological Administration has issued a blue typhoon warning (the lowest level on a four-tier scale); heavy rainfall is forecast in parts of Guangdong, Guangxi, and Hainan provinces, with rainfall totals of 10-15 cm (4-6 inches) possible in the affected area. Strong winds and rough seas are also forecast in coastal areas over the coming days.

Heavy rainfall in recent days has caused flooding in parts of central Vietnam. The inclement weather has displaced more than 7,600 people in Da Nang and Thua Thien Hue provinces and damaged more than 1,600 homes, predominantly in Da Nang City. Authorities have also reported that 15 fishermen are missing after two vessels capsized off the coast of central Vietnam.

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. 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.

Advice

Activate contingency plans in areas where officials forecast 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 (JTWC)
Vietnam National Center for Hydrometeorological Forecasting (NCHMF)