South China Sea: Typhoon Nesat tracking westward as of Oct. 18 /update 4

Event

Typhoon Nesat is tracking westward over the South China Sea Oct. 18. As of 14:00 CST, the system's center of circulation was approximately 480 km (298 miles) south-southwest of Hong Kong.

Forecast models indicate that the system will weaken slightly as tracks west-southwestward and makes a close approach to the north of the Paracel Islands late Oct. 18-early Oct. 19. The system is forecast to weaken further and become a tropical storm as it turns to track westward and then west-northwestward Oct. 19-20, making a close approach to Hainan Island, China. Nesat is then likely to weaken into a tropical depression before making landfall over southern Ha Tinh Province in north-central Vietnam Oct. 21. The storm system is expected to dissipate over central Laos Oct. 22. Some uncertainty remains in the track and intensity forecast, and changes could occur over the next few days.

As of Oct. 18, the China Meteorological Administration has issued a yellow typhoon warning (the second lowest level on a four-tier scale), advising that the storm will bring strong winds and rough seas to southern coastal waters and heavy rainfall to central, eastern, and southern parts of Hainan Island and the southern parts of the Leizhou Peninsula in Guangdong Province Oct. 18-19. Rainfall totals of 10-12 cm (3.9-4.7 inches) are forecast across southeastern parts of Hainan Island. The Honk Kong Observatory is maintaining Typhoon Warning Signal No. 3 (level 3 of 10) and has issued a Strong Monsoon Signal due to the passing of the storm to the south. Vietnam's National Center for Hydro-Meteorological Forecasting (NCHMF) has warned of strong winds and rough seas in coastal waters but as of Oct. 18 has not issued any warnings for land areas. Officials could update and possibly extend the coverage of weather alerts over the coming days.

Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, evacuations, and some employees' inability to reach work sites.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

China Meteorological Administration
Hong Kong Observatory
Vietnam National Center for Hydro-Meteorological Forecasting (NCHMF)