Manila, May 30 -- Two weather systems will bring rains over most of Luzon on Friday, the weather bureau said.

The southwesterly windflow will cause scattered rains and thunderstorms over the Ilocos, Cordillera, and Central Luzon regions.

Cagayan Valley will also experience scattered rains and thunderstorms due to the frontal system.

Moderate to heavy rains in these areas could result in flash floods or landslides, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said in its 4 a.m. bulletin.

The southwesterly windflow will also bring isolated rain showers or thunderstorms over Metro Manila, Calabarzon, and Mimaropa.

Localized thunderstorms will cause isolated rain showers over the rest of the a...