The southwest monsoon and a low pressure area are expected to bring light to occasional heavy rains in several parts of the country including Metro Manila, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said on Saturday.

According to the weather bureau, monsoon rains will affect Ilocos Region, Cagayan, Batanes, Zambales, Bataan, Cabite, Batangas, MIMAROPA (Occidental Mindoro at Oriental Mindoro, Marinduque, Romblon and Palawan), Antique and Aklan.

Metro Manila, rest of Luzon and Visayas will experience light to moderate occasional heavy rainfall.

Meanwhile, Pagasa's hydrology division said Saturday evening that rain in the past few days due to southwest monsoon slowed the rate of decline in the water level of Angat Dam.

"It has an effect (to the dam's water level) because based on our data on 6 am, the water level was 157.96 meters. However, our data as of 4 pm showed that the water level increased by 0.13 meters and is now at 158.09 meters," Pagasa hydrologist Tonya Serrano told The Daily Manila Shimbun in a phone interview.

Serrano added that due to the low pressure area, it is expected the dam's level will increase.

"It is possible to increase since it is expected to be rainy until Monday," she added.

But Serrano said this is not considered as an assurance that the water level in the dam will return to its normal operating level by July.

Serrano said a weak El Nino will persist but there will be two to three tropical depressions for the month of July.

''The required amount of rainfall is more or less 600 millimeters to achieve the normal operating water level of 180 meters," Serrano explained.

Pagasa warned residents in affected areas, especially those living in areas with high risk of flooding and landslides, to take precautionary measures and connect with local government and disaster risk reduction management offices.

Pagasa added that a low pressure area last located at 840 kilometers east of Virac, Catanduanes may develop into a tropical depression within 48 hours.

"The public and disaster risk reduction and management offices concerned are advised to continue monitoring for updates to be incorporated in the public weather forecast," Pagasa said in an advisory. Cristina Eloisa Baclig/DMS