Gulf of Tonkin: Tropical Storm Prapiroon tracking northwestward over the Gulf of Tonkin toward northeastern Vietnam late July 22 /update 4

Tropical Storm Prapiroon is tracking northwestward over the Gulf of Tonkin toward Quang Ninh Province in northeastern Vietnam late July 22. The storm previously made landfall near Wanning City, Hainan Province, China, early July 22 before passing over Hainan Island. As of 19:00 ICT, the system's center of circulation is approximately 244 km (152 miles) east-southeast of Hanoi, Vietnam.

Forecast models indicate that the weather system will continue to track northwestward and move over the island regions and then mainland Quang Ninh Province, Vietnam, early July 23. After landfall, Prapiroon is likely to weaken as it tracks northwestward over eastern Quang Ninh and into southeastern Lang Son Province close to the border with Guanxi Region, China, July 23. The system is forecast to weaken further into a depression as it turns to track eastward over central Lang Son Province late July 23-early July 24, before dissipating as it tracks southeastward into Bac Giang Province July 24. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

As of late July 22, the China Meteorological Administration is maintaining a yellow typhoon warning (the second lowest level on a four-tier scale); heavy rainfall is forecast over southwestern Guangxi Region in the coming hours and days, with rainfall totals of 10-12 cm (3.9-4.7 inches) expected late July 22-23. Strong winds are expected along the coasts of northwestern Hainan Province, southern Guangxi Region, and the Leizhou Peninsula in southwestern Guangdong Province.

Vietnam's National Centre for Hydro-Meteorological Forecasting (NCHMF) has warned of rainfall totals of 10-20 cm (4-8 inches) with localized higher amounts of over 30 cm (12 inches) over northeastern regions and rainfall of 5-10 cm (2-4 inches) with localized higher amounts of over 20 cm (8 inches) across northwestern regions and Thanh Hoa Province July 22-24. Strong winds are expected in the coastal areas of Quang Ninh Province, and rough seas are likely along the Gulf of Tonkin coast. Storm surge is possible in coastal areas between Quang Ninh to Nam Dinh provinces. Authorities will likely issue new alerts or update/rescind existing advisories depending on the progression of the storm system.

Authorities in Guangxi Region evacuated more than 26,000 tourists from Weizhou Island ahead of the storm's approach, with ferry services to and from the island suspended July 22-23. Ferry services have also been suspended in the Qiongzhou Strait. Officials also suspended high-speed rail services across Hainan Island and urban rail services in the city of Haikou July 21-22. Port and rail services in Hainan have started to resume operations during the afternoon July 22 as the storm moves away from the island. Initial reports indicate the storm felled several trees that blocked roads as it passed over Hainan, but no casualties or major damage has been reported.

In Vietnam, authorities in Quang Ninh Province have suspended permits for vessels to go offshore and banned overnight tourist stays at offshore islands from July 22; thousands of tourists have been evacuated from island locations ahead of the storm's approach. River ferries and other inland waterway transport services have also been suspended in Quang Ning. Officials in Nam Dinh Province have enforced a suspension of all sea activities from July 22.

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.