South China Sea: Typhoon Cempaka tracking northwest in South China Sea as of evening July 20; landfall likely near Yanjiang late July 20 /update 3

Event

Typhoon Cempaka is tracking northwestward in the South China Sea as of the evening of July 20. As of 17:00 CST July 20, the system's center of circulation was approximately 220 km (136 miles) west-southwest of Hong Kong. Forecast models indicate the typhoon will weaken into a Tropical Storm from the afternoon of July 21 after making landfall near Yangjiang, Guangdong Province, late July 20. The storm will weaken into a Tropical Depression as it veers westward along the coast of Guangdong through the evening of July 22. The Depression will then move into the South China Sea and strengthen in a Tropical Storm again by the afternoon of July 23. Significant uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

Government Advisories
As of late July 20, the China Meteorological Administration continues to issue an orange-level typhoon warning (i.e., the second-highest in a four-tiered system) for coastal areas of central and western Guangdong Province, as well as coastal areas of Guangxi and Hainan, indicating that winds of up to 137 kph (85 mph) are possible in some areas within 24 hours. 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 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 Storm Cempaka will likely bring heavy rainfall, strong winds, and storm surge across the affected area through at least July 24. Impacts will likely be felt across central and western Guangdong, southeastern Guangxi, and northeastern Hainan. Forecast models indicate up to 20 cm (8 inches) of rainfall are possible per day in parts of western Guangdong.

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. Prolonged swells and storm surge generated by the system will likely result in coastal flooding as the system approaches land. A persistent onshore flow could make it difficult for the 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 as it moves across China's far southeast. 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 24. 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 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 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
Joint Typhoon Warning Center