Two low-pressure areas (LPAs) and a tropical depression are being monitored as the southwest monsoon, locally known as the "habagat," continues to threaten Luzon and the Visayas, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said Tuesday.

In its 10:00 a.m. tropical cyclone monitoring bulletin, the state weather bureau said both LPAs have a high chance of developing into a tropical depression within the next 24 hours.

The nearer LPA was located 400 kilometers (km) west of Calayan, Cagayan, outside the Philippine Area of Responsibility (PAR), the zone within which the national meteorological agency monitors and names weather disturbances affecting the country. The farther and more recently developed LPA was spotted 1,170 km east of Extreme Northern Luzon.

PAGASA was also monitoring a tropical depression outside PAR, located exactly 3,160 km east of Northeastern Mindanao.

The agency is expected to provide new updates about the disturbances by 5:00 p.m.

Meanwhile, in an 11:00 a.m. advisory, PAGASA said the southwest monsoon, which triggered widespread flooding in Metro Manila and nearby areas on Monday, will continue to bring up to intense rainfall over several areas, posing risks of flooding events and landslides.

Intense rainfall, equivalent to 100 to 200 millimeters (mm) of rain, is expected to fall over Zambales, Bataan, Cavite, Batangas and Occidental Mindoro. PAGASA warned of possible flooding events in urbanized, low-lying and near-river areas under this rainfall condition.

Areas of Metro Manila, La Union, Benguet, Pangasinan, Ilocos Sur, Abra, Tarlac, Pampanga, Bulacan, Nueva Ecija, Laguna, Rizal, Oriental Mindoro and Antique will experience heavy rains, or rainfall between 50 and 100 mm. Under these conditions, localized flooding is likely, especially in urbanized, low-lying and near-river areas.

PAGASA said similar areas are still expected to experience heavy downpours until Friday noon.

The southwest monsoon is a seasonal wind pattern marked by warm, moist southwesterly winds that regularly bring prolonged rain to the western sections of the Philippines during the rainy season, which in these western areas typically runs from June to November. The habagat can sustain days of rain even without a tropical cyclone making landfall, which is why monsoon episodes remain a recurring flood and landslide risk for western Luzon, Metro Manila and neighboring provinces even while the systems being monitored remain outside PAR. — Edg Adrian A. Eva