East China Sea: Tropical Storm Chanthu tracking slightly southeastward in East China Sea Sept. 14 /update 1

Event

Tropical Storm Chanthu is tracking slightly southeastward but is largely stationary in the East China Sea off Shanghai, China, Sept. 14. As of 17:00 CST, the storm's center of circulation was approximately 574 km (357 miles) west-southwest of Sasebo, Japan.

The storm is forecast to remain largely stationary in the East China Sea off Shanghai through the afternoon of Sept. 16 while weakening slightly. The system will then track northeastward between South Korea and Japan, making a close approach to Jeju Province, South Korea, early Sept. 17, and Nagasaki Prefecture, Japan, later that day. Chanthu is forecast to track northeastward in the Sea of Japan, along Japan's northwestern coast, before making landfall over far northern Shimane Prefecture, Japan, late Sept. 17. Subsequent landfalls are likely over northern Ishikawa Prefecture, Japan, early Sept. 18, then Niigata Prefecture later that day. Following landfall, Chanthu is forecast to weaken as it tracks northeast across Niigata, Yamagata, then Miyagi prefectures before dissipating over far northeastern Miyagi Prefecture the afternoon of Sept. 18. The storm's track and intensity forecast remain uncertain, and the system may change accordingly over the coming days.

In response to the storm, authorities have evacuated at least 331,000 people from Shanghai and 610,200 from Zhejiang Province.

Government Advisories
As of Sept. 14, the China Meteorological Administration has issued a yellow typhoon warning due to Chanthu, warning that strong winds are forecast in the central and southern parts of the Yellow Sea, most of the East China Sea, Hangzhou Bay, and the Yangtze Estuary as well as the coasts of northern Zhejiang, Shanghai, and Jiangsu provinces. Officials also forecast moderate-to-heavy rains and locally heavy rains of 5-7 cm (2-3 inches) in some areas of eastern Shanghai and northeastern Zhejiang provinces through Sept. 15.

The Japan Meteorological Agency has issued the following advisories:

• Orange (second-lowest level on a four-tier scale) landslide warnings due to heavy rain: Kagoshima Prefecture

• Yellow (lowest level on a four-tier scale) thunderstorm, heavy rain, flood, and large wave warnings: Kumamoto, Kochi, Miyazaki, Nagasaki, Oita, Okinawa, Saga, and Yamaguchi prefectures

The Korean Meteorological Administration has issued a windstorm advisory for the waters off the country's southwestern and western coasts, including off Jeju Island. Heavy rain and strong wind advisories are in effect for most of Jeju Province.

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 cannot be discounted if weather conditions prove particularly hazardous.

Hazardous Conditions
The storm will likely bring heavy rainfall, strong winds, and rough seas to eastern mainland China, Japan, and South Korea over the coming days. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed or a lack of 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.

Flights at Shanghai Pudong International Airport (PVG) and Shanghai Hongqiao International Airport (SHA) have resumed Sept. 14. Some subway services in Shanghai are suspended. All trains on the high-speed rail service on the Hangzhou-Ningbo, Beijing-Shanghai, Shanghai-Kunming, and Ningbo-Taiwan-Wenzhou routes have been canceled through at least Sept. 14. Authorities have also suspended some port operations at the Shanghai and Zhejiang ports. Korean officials have also canceled at least five ferries from Jeju Province.

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.

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 the 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 or typhoon 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
Taiwan Central Weather Bureau
China Meteorological Administration (Mandarin)
Japan Meteorological Agency (Japanese)
Korea Meteorological Administration (Korean)