The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said the cyclone-enhanced southwest monsoon or "habagat" is expected to be the dominant weather system that could bring light to at times heavy rains over some parts of the country in the next few days.
PAGASA said the severe tropical storm "Fabian" (international name "In-fa") and a tropical storm with the international name "Cempaka" are currently enhancing the habagat.
Fabian and was estimated at 1,075 kilometers (km) east-northeast of extreme northern Luzon around 4 p.m.
It has maximum sustained winds of 95 kilometers per hour (kph) near the center and gustiness of up to 115 kph while barely moving over the Philippine Sea.
Meanwhile, Cempaka was at 945 km west of extreme northern Luzon or outside the Philippine area of responsibility.
Due to the enhanced habagat, scattered to widespread moderate to at times heavy monsoon rains may prevail over Ilocos Norte, Ilocos Sur, La Union, Pangasinan, Zambales, Bataan, Occidental Mindoro, and Palawan in the next 24 hours.
Scattered light to moderate rains with occasional heavy rains may also affect Metro Manila, Batanes, Cagayan, Abra, Apayao, Benguet, Ifugao, Kalinga, Mountain Province, Pampanga, Tarlac, Bulacan Cavite, Laguna, Batangas, Rizal, Quezon, Antique, Aklan, Capiz, Iloilo, Guimaras, and Negros Occidental.
Meanwhile, the rest of the country will have partly cloudy to cloudy conditions with rain showers or thunderstorms.
PAGASA warned against possible flash floods or rain-induced landslides during heavy or prolonged rainfall, particularly in areas that are highly susceptible to these hazards.
Track and intensity outlook
Based on Fabian's latest forecast scenario, the hoisting of tropical cyclone wind signals over any part of the country remains less likely.
However, PAGASA still advised residents and disaster managers in Batanes and Babuyan Islands to continuously monitor the tropical cyclone bulletins as any further southward shift in the orientation of Fabian's forecast track may result in the hoisting of Signal No. 1 over these areas.
In the next 12 hours, Fabian will begin to move generally west-northwestward.
"Due to the southward shift in the orientation of the track, the tropical cyclone may exit the Philippine area of responsibility by Thursday afternoon or evening (July 22). Afterward, Fabian will move generally westward and pass close to the Miyako, Yaeyama, and Senkaku Islands of the Ryukyu archipelago on Wednesday afternoon (July 21) through Thursday afternoon. A west-northwestward turn is likely by Friday (July 23) as Fabian passes over the sea north of Taiwan and forecast to make landfall over Fujian, China," PAGASA said.
Fabian will likely intensify into a typhoon by Tuesday afternoon or evening, July 20.
"(Its) peak intensity may be reached by Wednesday evening or Thursday early morning. Slight weakening may occur by Friday morning as the circulation of Fabian interacts with the rough terrain of Taiwan during its passage to the north of the island and will weaken into a severe tropical storm by Saturday afternoon (July 24)," it added.