Philippine Sea: Typhoon Surigae tracking northeastward off the northern Philippines early April 22 /update 13

Event

Typhoon Surigae (known in the Philippines as Bising) is tracking northeastward in the Philippine Sea early April 22. As of 08:00 PHST, the storm's center of circulation was approximately 700 km (435 miles) northeast of Manila. Forecast models indicate Surigae will slowly weaken as it veers eastward towards the northern Pacific Ocean April 23 and transitions into an extratropical cyclone by April 25. Projections do not indicate landfall. Some 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) continues to maintain Tropical Cyclone Wind Signal warnings as of early April 22. The Tropical Cyclone Wind Signal No. 1 is in place for parts of Luzon, including Batanes, eastern areas of Cagayan, and the northeastern portion of Isabela provinces. 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.

Authorities have evacuated more than 100,000 people across the Philippines, including Virac Municipality in Catanduanes Province and the central and eastern parts of Northern Samar Provinces, as of April 22. Further localized evacuations may occur if weather conditions prove particularly hazardous. Reports indicate at least four storm-related fatalities in the Visayas as of April 22; severe weather conditions also prompted a cargo vessel accident off Surigao Del Norte Province, northern Mindanao.

Hazardous Conditions
The storm may bring heavy rainfall, strong winds, and rough seas to coastal areas of the northern 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 likely continue to produce damaging wind gusts as it continues to track parallel to the eastern Philippines. Power disruptions have affected parts of the Philippines, including Camarines Sur, Masbate, and Southern Leyte provinces, as of April 22. Additional 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. The system has also led to landslides that block roads in parts of Catanduanes Province, including Virac Municipality.

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