Philippine Sea: Tropical Cyclone Surigae tracking northwestward in the Philippine Sea as of April 17 /update 4

Event

Typhoon Surigae (known in the Philippines as Bising) is strengthening as it continues tracking northwestward in the Philippine Sea April 17. As of 09:00 PWT April 17, the storm's center of circulation was approximately 489 km (304 miles) northwest of Kayangel, Palau. Forecast models indicate the storm will further strengthen as a typhoon through early April 18 before veering slightly northward off the eastern Philippines April 19. As of April 17, projections do not indicate landfall; the storm will maintain a parallel course off the eastern Philippines in the coming days. Significant uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

Government Advisories
The US National Weather Service continues to warn of high waves in Koror, Palau, as of April 17. The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) announced that moderate to heavy rains could occur in parts of the eastern Visayas and Luzon's Bicol Region through April 19. PAGASA has also issued Tropical Cyclone Wind Signal Number 1 for Albay, Catanduanes, and Sorsogon provinces, Masbate Province's Ticao Island, and the eastern portion of Camarines Sur Province in Luzon Region; Biliran, Eastern Samar, Leyte, Northern Samar, Samar, and Southern Leyte provinces and Cebu Province's Camotes Islands in Visayas Region; and Dinagat Islands, Surigao del Norte, and Surigao del Sur provinces in Mindanao. Taiwan's Central Weather Bureau has not released any alerts as of April 17. 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 Palau and the eastern Philippines. 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
Local officials in the Philippines have suspended all land and sea travel from Luzon's Bicol Region to Mindanao and Visayas as of April 17 until further notice. Additionally, on top of 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 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