Southwest Monsoon Continues to Drench Luzon with No Immediate Relief in Sight

The southwest monsoon, locally known as habagat, persisted in bringing heavy rains across much of Luzon on Sunday, August 9, with forecasts indicating that the wet conditions will continue into the coming week. The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) reported in a briefing after 5 p.m. that significant rainfall is expected in Metro Manila and over 20 provinces within the next 24 hours, with the province of Benguet in the Cordillera Administrative Region likely to experience the most intense precipitation.

PAGASA provided a detailed 72-hour rainfall outlook from the southwest monsoon as of Sunday evening. From Sunday afternoon, August 9, to Monday afternoon, August 10, Benguet is forecast to receive intense to torrential rain exceeding 200 millimeters. Heavy to intense rain ranging from 100 to 200 millimeters is expected in Ilocos Sur, La Union, Zambales, Bataan, Metro Manila, Rizal, Cavite, and Occidental Mindoro. Meanwhile, moderate to heavy rainfall between 50 and 100 millimeters is predicted for Ilocos Norte, Pangasinan, Abra, Kalinga, Mountain Province, Ifugao, Nueva Vizcaya, Tarlac, Nueva Ecija, Pampanga, Bulacan, Batangas, Laguna, Oriental Mindoro, and Antique.

The rain is forecast to persist into Monday afternoon, August 10, through Tuesday afternoon, August 11, with heavy to intense rainfall continuing in La Union, Benguet, Zambales, Bataan, and Occidental Mindoro. Moderate to heavy rain is expected in Ilocos Sur, Pangasinan, Abra, Tarlac, Nueva Ecija, Pampanga, Bulacan, Metro Manila, Cavite, Batangas, Oriental Mindoro, and Antique. From Tuesday afternoon, August 11, to Wednesday afternoon, August 12, heavy to intense rain will likely affect Zambales, Bataan, and Occidental Mindoro, while moderate to heavy rain is expected in La Union, Ilocos Sur, Pangasinan, Benguet, Tarlac, Pampanga, Nueva Ecija, Cavite, and Batangas.

In addition to these areas, scattered rain and thunderstorms are anticipated Sunday evening across other parts of Luzon, Western Visayas, and the Negros Island Region due to the southwest monsoon. The continuous rainfall has already caused flooding and landslides in various regions, including Metro Manila.

In Marikina City, the Marikina River's water level was recorded at 17.2 meters as of 7 p.m. on Sunday, slightly down from 17.5 meters an hour earlier but still at the second alarm level. This level prompts preemptive evacuation for residents in flood-prone areas. Should the river reach 18 meters, a third alarm would be declared, triggering mandatory evacuations.

Meanwhile, the La Mesa Dam in Quezon City reached a water level of 79.87 meters as of 7 p.m., surpassing the critical threshold of 79.50 meters. The dam is expected to overflow if it reaches the spilling level of 80.15 meters, potentially impacting communities in Quezon City, Caloocan City, Malabon City, Navotas City, and Valenzuela City, especially those near the Tullahan River.

PAGASA is also monitoring Tropical Storm Peilou, located approximately 2,200 kilometers east of extreme Northern Luzon as of 3 p.m. Sunday. Peilou is moving east-southeast away from the Philippine Area of Responsibility (PAR) at 25 kilometers per hour, with maximum sustained winds of 65 km/h and gusts up to 80 km/h. Although Peilou is unlikely to enter PAR, it may enhance the southwest monsoon in the coming days, according to PAGASA Weather Specialist Charmagne Varilla.

Earlier in August, PAGASA forecasted that two to four tropical cyclones could develop within or enter PAR. So far, Tropical Depression Luis and Tropical Storm Maymay (Kujira) have occurred. Another system, Typhoon Dolphin, did not enter PAR but contributed to strengthening the southwest monsoon.

The National Disaster Risk Reduction and Management Council reported on Sunday morning that the combined effects of the enhanced southwest monsoon, Luis, and Maymay have resulted in at least six fatalities and seven injuries. The persistent rains and associated hazards continue to pose significant risks to affected communities across Luzon.