South China Sea: Tropical Depression Cempaka tracking southward over Gulf of Tonkin July 23 /update 9

Event

Tropical Depression Cempaka tracking southward over Gulf of Tonkin July 23. As of 16:00 ICT, the system's center of circulation was approximately 180 km (112 miles) east of Hanoi, Vietnam. Forecast models indicate the storm will maintain its strength as it tracks southward and then southeastward over the Gulf of Tonkin. Cempaka is likely to weaken gradually as it turns to track eastward and make a close approach to western Hainan Island before dissipating early July 25. Some uncertainty remains in the track and intensity forecast, and some changes could occur in the coming days.

Government Advisories
As of July 23, the following advisories are in effect:

• The China Meteorological Administration has issued blue heavy rain alerts (the lowest alert level on a four-tiered scale) for parts of southern Guangxi and northern Hainan. Additional rainfall of up to 18 cm (7 inches) is possible in the affected areas.

• The Vietnam National Centre for Hydro-Meteorological Forecasting has warned of strong winds and large waves in the Gulf of Tonkin with winds of up to 25 knots (45 kph/30 mph) and waves of 2-4 meters (6.5-13 feet). A heavy rain warning is also in place in the Northeast, North Central Coast, and Red River Delta regions.

Authorities will likely issue new warnings throughout the system's progression in the coming days. Weather warnings could remain active even after the storm's immediate threat has diminished, as some areas may still be highly susceptible to rain-induced hazards; this is especially true in areas previously impacted by tropical systems earlier this season.

Hazardous Conditions
Tropical Depression Cempaka will likely bring heavy rainfall, strong winds, and storm surge in parts of the affected area through at least July 25. Impacts will likely be felt in the Northeast and Red River Delta regions of Vietnam, and possibly in areas of southern Guangxi and Hainan, China.

Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed stormwater 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. A persistent onshore flow could make it difficult for storm surge to recede and water levels to decrease in coastal river catchments.

In addition to heavy rain, flooding, and storm surge, the system could produce damaging wind gusts in affected regions. Tropical-storm-force wind gusts may occur. Localized power outages are possible due to uprooted trees and toppled utility lines.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions through at least July 25. 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 weather conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Advice

Activate contingency plans in areas where officials forecast inclement weather 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 high potential for 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.

Plan accordingly for commercial, transport, and logistics disruptions in areas in the path of the storm. 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.

Resources

China Meteorological Administration
Vietnam National Centre for Hydro-Meteorological Forecasting (Vietnamese)
Joint Typhoon Warning Center