South China Sea: Tropical Storm Kompasu tracking westward over South China Sea Oct. 13; landfall forecast in Hainan Province late Oct. 13 /update 4

Event

Tropical Storm Kompasu (also known as Maring in the Philippines) is tracking westward over the South China Sea Oct. 13. As of 05:00 CST, the storm's center of circulation was approximately 357 km (222 miles) south of Hong Kong, China. Forecast models indicate the system will maintain its current intensity as it tracks westward before making landfall in Hainan Province, China, late Oct. 13. Kompasu will then likely weaken as it continues its westward track over Hainan Province and across the Gulf of Tonkin; the system is subsequently forecast to make another landfall as a weak tropical storm or strong tropical depression in Vietnam's Nghe An Province late Oct. 14. After making landfall in Vietnam, Kompasu is forecast to track west-southwestward before dissipating over Laos' Vientiane Province by early Oct. 16. The storm's track and intensity forecast remain somewhat uncertain, and the system may change accordingly over the coming days.

Government Advisories
The China Meteorological Administration has issued a yellow typhoon warning due to the storm, forecasting that strong winds will affect coastal areas of Fujian, Guangdong, Guangxi, Hainan, and Zhejiang provinces until at least Oct. 13. Heavy rainfall is forecast for northeastern Fujian, eastern and southern Guangdong, central and eastern Hainan, and central and eastern Zhejiang provinces over the same period; notably, rainfall totaling 25-28 cm (10-11 inches) is forecast for eastern and central Hainan Province through late Oct. 13.

Vietnamese officials have warned of heavy rain across Northern Vietnam Region and Quang Tri Province Oct. 13-15. Very heavy rain is forecast from Thanh Hoa Province to Quang Binh Province over the same period.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) has discontinued tropical cyclone wind signals (TCWS) in connection with Kompasu. However, PAGASA officials have warned that the southwest monsoon, enhanced by the tropical system, will bring moderate-to-heavy rainfall to the provinces of Bataan, Zambales, Aurora, Occidental Mindoro, and Palawan through late Oct. 13, possibly resulting in flash flooding and landslides. Flooding and landslides are also possible in areas of northern Luzon saturated by recent Kompasu-related rainfall.

Authorities will likely issue new warnings or update existing advisories throughout the system's progression in the coming days. Weather warnings could remain active even after the system's immediate threat has diminished, as some areas may still be highly susceptible to rain-induced hazards. The possibility of localized evacuations remains possible if weather conditions prove particularly hazardous.

Hazardous Conditions
The storm may bring heavy rainfall, strong winds, and rough seas to coastal areas of far southern China and central and northern Vietnam over the coming days. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with inadequate 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. Prolonged swells and storm surge generated by the system will likely result in coastal flooding. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments.

Transport
Inclement weather associated with the storm could trigger localized business, transport, and utility disruptions. Floodwaters and debris flows could render some bridges 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 improve. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Health
Stagnant pools of water during and after flooding increase the incidence of insect- and waterborne diseases, such as dengue fever, cholera, and malaria. The threat of these disease outbreaks is usually elevated in low-income or underdeveloped areas of major urban centers due to the presence of incomplete or open sewer lines. The latent threat of waterborne contaminants from inundated industrial sites cannot be discounted; 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
Cambodia Department of Meteorology
China Meteorological Administration
Philippine Atmospheric, Geophysical and Astronomical Services Administration
Taiwan Central Weather Bureau
Thai Meteorological Department
Vietnam National Centre for Hydro-Meteorological Forecasting (Vietnamese)