South China Sea: Tropical Depression 05W forms in the South China Sea June 12

Event

Tropical Depression 05W formed in the South China Sea, near Hainan, China, June 12. As of 16:00 ICT, the storm was approximately 110 km (68 miles) northwest of Sanya, China, and 385 km (240 miles) southeast of Hanoi, Vietnam. The depression is forecast to strengthen gradually, likely reaching tropical storm intensity by evening June 12, as it tracks northwestward. The storm is forecast to make landfall in Nam Dinh Province, Vietnam, June 13. The system will turn northward and begin weakening rapidly after making landfall; models indicate the system will dissipate in northern Vietnam, June 14. However, some uncertainty remains in the track and intensity forecasts, and significant changes could occur before landfall.

Hazardous Conditions
Tropical Depression 05W made landfall in southeast Hainan at around 09:30 June 12. Forecasts indicate that the system will continue bringing heavy rainfall to the island and coastal areas of Guangxi and southwestern Guangdong through midday June 13; up to 18 cm (7 inches) of rain could occur in southern Hainan before the system moves away. Heavy rainfall will also affect northern Vietnam, where meteorologists predict 15-25 cm (6-10 inches) of precipitation will fall through June 14 and northeastern Laos. Strong winds gusts are also likely to impact Hainan and northern Vietnam through June 13. Storm surge is likely in coastal areas.

Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, and rivers or urban areas with easily overwhelmed drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Rain-induced landslides are possible in steeply sloped terrains. Flooding could isolate some communities for several days. Prolonged swells and storm surge generated by the system will likely result in coastal flooding as the system approaches land. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments.

In addition to the heavy rain, flooding, and storm surge, Tropical Depression 05W may produce damaging wind gusts as it approaches the affected area. Tropical-storm-force wind gusts over 50 knots (90 kph, 60 mph) cannot be ruled out, especially in areas just to the north of the center of circulation. Localized power outages due to uprooted trees and toppled utility lines are possible.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions in Hainan, China, and northern Vietnam through June 14. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion, while strong winds will pose a hazard to high-profile vehicles. Heavy rain and low visibility may trigger flight disruptions at regional airports. Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after conditions improve. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Advice

Activate contingency plans in areas where officials forecast storm conditions. Heed all evacuation orders. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the high 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 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. Keep any necessary medications in a waterproof container.

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
Vietnamese Hydrometeorological Service Vietnamese