Rains in Cagayan, Central Luzon, Eastern Visayas, and the Caraga region might cause flash floods and could trigger landslides, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said Thursday.

Weathermen said that the easterly winds blowing from the Pacific Ocean over Mindanao has intensified rain activities of northeast monsoon.

PAGASA deputy director for operations  Nathaniel Cruz explained that the interaction of the Northeast monsoon, which blows from Japan and China over Luzon and Visayas, with the easterly waves, has also generated wind strength of 50 to 60 kilometers per hour (kph).

“The interaction of the two windflow has extended the effect of Northeast monsoon that could last until today, which has brought light to moderate rains in Luzon particularly in the easter sections this week,” Cruz said.

PAGASA has issued flood forecast and advisories after expecting the wind flows to bring light to moderate rains over the Cagayan River Basin, as well as rivers in Central Luzon, Eastern Visayas, and the Caraga region.

PAGASA Hydrometeorological Division Chief Susan Espinueva said that a total of 112 millimeters (mm) of rainfall has been dumped in Cagayan River since November 3, adding that another 50 mm of rains are expected to come down along the basin Friday morning.

Espinueva has warned of gradual rise of the Upper Main Cagayan River and its tributaries like Gagano and Diadi rivers, the Middle Main Cagayan River and its tributaries Magat river, Pinacanauan rivers of Ilagan and San Pablo, all in the province of Isabela.

She said that flooding has occurred in the low-lying areas of Santiago City, Echague, Angadanan, Alicia and Cauayan in Isabela province since Wednesday.

“Flooding has occurred and expected to persist within the next 12 hours in the low-lying areas of Reina Mercedes, Naguilian, Gamu, Ilagan, Tumauini, Delfin Albano, Cabagan, Sto. Tomas, San Pablo, and Sta. Maria,” she said.