Philippine Sea: TD 18W forms east of the northern Caraga Region, the Philippines Sept. 6; landfall forecast in Aurora Province Sept. 9

Event

Tropical Depression 18W (known in the Philippines as Jolina) has formed in the Phillippine Sea, east of the northern Caraga Region, the Philippines Sept. 6. As of 11:00 PHT, the storm's center of circulation was approximately 839 km (521 miles) east-southeast of Manila, Philippines. Forecast models indicate the system will strengthen into a tropical storm strength as it tracks northwest towards the Eastern Visayas Region through late Sept. 6. The system is projected to strengthen further as it makes a close approach to the Eastern Visayas Region early Sept. 7 and continues tracking northwest in the Philippine Sea, roughly parallel to the eastern coasts of Eastern Visayas, Bicol, and Calabarzon regions through early Sept. 9. The storm is likely to make landfall as a tropical storm over Aurora Province, Central Luzon Region, the afternoon of Sept. 9. Following landfall, 18W is forecast to weaken slightly as it tracks northwest across southern Cagayan Valley, southern Cordillera Administrative Region, then southern Ilocos Region, and exit into the South China Sea early Sept. 10. 18W is likely to continue tracking northwest across the South China Sea through at least early Sept. 11. The storm's track and intensity forecast remain somewhat uncertain, and the system may change accordingly over the coming days.

Government Advisories

As of Sept. 6, officials in the Philippines forecast heavy rains in parts of Eastern Samar, Dinagat Islands, and Surigao del Norte, including Siargao and Bucas Grande Islands. Light to moderate rain is forecast over Northern Cebu, Bohol, Camiguin, and the rest of Eastern Visayas. Additionally, authorities have issued a Tropical Cyclone Wind Signal 1 for the Sorsogon Province in Luzon and Northern Samar, Samar, and Eastern Samar provinces in Eastern Visayas Region, as well as Dinagat, Siargao, and Bucas Grande Islands in Mindanao. 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 may bring heavy rainfall, strong winds, and rough seas to coastal areas of the southern Philippines 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 as the system approaches land. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments. Waves of 1.2-2.8 m (4-9 feet) are forecast for the eastern coasts of Visayas and Mindanao through early Sept. 7.

Transport
In addition to the immediate threat to personal safety, 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 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 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 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 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. Keep any necessary medications in a waterproof container.

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
Philippine Atmospheric Geophysical and Astronomical Services Administration