Manila, Dec. 12 -- Three weather systems are forecast to bring rains over the country, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said Friday.

In its 4 a.m. advisory, the weather bureau said the Bicol Region, Quezon, Northern Samar, and Eastern Samar will have cloudy skies with scattered rains and isolated thunderstorms due to the shear line.

The shear line, a convergence of cold and warm winds that triggers rainfall, will also prevail over Metro Manila and other parts of Calabarzon (Cavite, Laguna, Batangas, Rizal, and Quezon).

Cagayan, Isabela, and Aurora will have cloudy skies with rains due to the northeast monsoon (amihan).

Ilocos Region, Cordillera Administrative Region, the rest of...