Philippine Sea: Super Typhoon Surigae tracking northwestward in the Philippine Sea near Philippines late April 18 /update 7

Event

Super Typhoon Surigae (known in the Philippines as Bising) continues to track northwestward in the Philippine Sea late April 18. As of 20:00 PHST, the storm's center of circulation was approximately 600 km (373 miles) east-southeast of Manila. Forecast models indicate the storm will continue to weaken as it veers northward off the eastern Philippines coastline through April 20. Projections do not indicate landfall; the storm will maintain a parallel course off the eastern Philippines in the coming days. Uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

Government Advisories
The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) maintains a Tropical Cyclone warning as of 17:00 PHST April 18. The Tropical Cyclone Wind Signal No. 2 is in effect for Catanduanes in Luzon, Northern Samar, Eastern Samar, and Samar in the Visayas. Additionally, the Tropical Cyclone Wind Signal No. 1 is in place for the eastern portion of Camarines Norte (San Lorenzo Ruiz, San Vicente, Vinzons, Talisay, Daet, Mercedes, Basud), Camarines Sur, Albay, Sorsogon, and Masbate including Burias and Ticao Islands in Luzon; Biliran, Leyte, Southern Leyte, and the northern portion of Cebu (Tabogon, Borbon, San Remigio, Bogo City, Medellin, Daanbantayan) including Bantayan and Camotes Islands in Visayas; and Dinagat Islands, Siargao Islands, 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 eastern Philippines in 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.

In addition to the heavy rainfall, flooding, and storm surge, Surigae will produce damaging wind gusts as it continues to track towards the eastern Philippines. Widespread and prolonged power outages due to uprooted trees and toppled utility lines are possible.

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. Local officials in the Philippines have reportedly suspended land and sea travel in some eastern areas.

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 incomplete or open sewer lines. The latent threat of waterborne contaminants from inundated industrial sites cannot be discounted; exposure to raw sewerage 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 all evacuation orders. 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
US National Weather Service
Taiwan Central Weather Bureau