Philippine Sea: Typhoon Rai tracking west-northwestward in Philippine Sea late Dec. 15; landfall forecast over northern Caraga Region Dec. 16 /update 4

Event

Typhoon Rai (known locally in the Philippines as Odette) was tracking west-northwestward in the Philippine Sea late Dec. 15. As of 20:00 PHT, the storm's center of circulation was approximately 1,135 km (705 miles) east-southeast of Manila, Philippines. Forecast models indicate the system will slightly strengthen over the coming hours as it tracks westward toward the Philippines before it makes landfall over northern Caraga Region Dec. 16. The system will then slightly weaken as it tracks across the central Philippines and makes further landfalls over parts of Eastern Visayas, Central Visayas, and Western Visayas regions late Dec. 16 through early Dec. 17. After crossing the Sulu Sea Dec. 17, Rai is forecast to make landfall over northern Palawan island late Dec. 17. The storm system is subsequently forecast to maintain typhoon strength as it enters the South China Sea and is then likely to strengthen as it gradually turns to track northwestward toward southern China Dec. 18-19, before turning further to the north and weakening into a severe tropical storm south of Hainan, China, Dec. 20. Some uncertainty remains in the track and intensity forecast, and changes could occur over the next few days.

Authorities have notably begun preemptive evacuations across high-risk areas, including in Caraga Region and the Visayas, ahead of the storm's forecast landfall.

Government Advisories
The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) has issued the following warnings:

• Tropical Cyclone Wind Signal (TCWS) 3: Dinagat Islands, Surigao del Norte, northern Agusan del Norte, and northern Surigao del Sur

• TCWS 2: Southeastern Masbate, central and southern Eastern Samar, central and southern Samar, Biliran, Leyte, Southern Leyte, Cebu, Bohol, Negros Oriental, Siquijor, Negros Occidental, Guimaras, eastern Iloilo, the rest of Surigao del Sur, the rest of Agusan del Norte, Agusan del Sur, northern Bukidnon, eastern and central Misamis Oriental, and Camiguin

• TCWS 1: Catanduanes, Camarines Sur, Albay, Sorsogon, the rest of Masbate (including Ticao and Burias Islands), Marinduque, Romblon, southern Quezon, southern Batangas, Oriental Mindoro, Occidental Mindoro, northern and central Palawan (including Calamian, Cagayancillo and Cuyo Islands), northern Samar, the rest of Eastern Samar, the rest of Samar, Aklan, Antique, Capiz, the rest of Iloilo, northern Davao Oriental, northern Davao de Oro, northern Davao del Norte, the rest of Misamis Oriental, Misamis Occidental, central Bukidnon, northern Lanao del Norte, northern Lanao del Sur, northern Zamboanga del Norte, and northern Zamboanga del Sur

Authorities have warned of heavy to intense rains over eastern areas from late Dec. 15 and across much of the central Philippines through late Dec. 17, continuing into Dec. 18 in Palawan Province. There is a moderate to high risk of storm surge of up to 3 meters (10 feet) which may cause flooding in coastal areas of Surigao del Norte, Dinagat Islands, Agusan del Norte, Eastern Samar, Southern Leyte, Negros Occidental, Guimaras, and some localities in Camiguin, Central Visayas, Panay Island, and the northern portion of Palawan.

Authorities will probably 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. Officials may announce additional evacuations if weather conditions prove particularly hazardous.

Hazardous Conditions
Typhoon Rai will likely bring heavy rainfall, strong winds, and rough seas to most of the Visayas, southern Luzon, and northern Mindanao regions of the Philippines in the coming days. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, and rivers, as well as in 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 sea swells and storm surge generated by the system could result in coastal flooding as the system approaches land. Persistent onshore flow could make it difficult for surge to recede and for water levels to decrease in coastal river catchments.

In addition to forecast heavy rain, flooding, and storm surge, the storm could produce damaging wind gusts. 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 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 or typhoon 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 and any necessary medications 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.

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