Wind convergence, thunderstorms blamed for flash floods in Metro

MANILA, Philippines - Wind convergence and a series of thunderstorms brought down torrential rains before dawn yesterday, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said.

Pagasa weather forecaster Leny Ruiz clarified that the merging of wind systems from two different directions and several thunderstorms – not a typhoon – caused the heavy downpour that flooded several parts of Metro Manila.

“There was a wind convergence coming from the Southwest and Northeast and the line of convergence was over Metro Manila and the Bicol Region. This affected the weather in Metro Manila,” Ruiz said.

It was also recorded that during the period from 8 a.m. of Aug. 21 to 8 a.m. Aug. 22, there was a total of 100 millimeters of rainfall in Metro Manila and the large volume of the rainfall was concentrated for four hours, from 2 a.m. to 6 a.m. yesterday.

Usually Pagasa records one thunderstorm per day but on Friday night, it monitored a series of thunderstorms.

Ruiz said wind convergence is common during the rainy season. Lately Pagasa has advised the public to expect isolated thunderstorms and showers in the afternoon and at night.

Unfortunately, Pagasa is still installing the Doppler Radars that would help weather experts estimate volume of rainfall and where it would rain. As of now, “we still have no capability,” Ruiz said.

The Metropolitan Manila Development Authority (MMDA) Metrobase said the areas worst hit by floods are in Manila and Quezon City.

Laong Laan and Altura in Manila were submerged in two feet of water, while floodwaters in Mount Carmel and N. Domingo in Quezon City reached at least three feet before subsiding just before 8 a.m.

Floodwaters also affected San Juan Mariano in San Juan City; and Libertad and Maricaban in Pasay City.

At around 12 noon, floodwaters subsided in most of the affected areas, according to the MMDA, except for the stretch of España Boulevard in Manila.

The MMDA blamed the recurring floods on illegal settlers and residents’ improper disposal of garbage.

Meanwhile, Pagasa said that as of 5 p.m. yesterday, a low-pressure area (LPA) was seen at 560 kilometers northeast of Basco, Batanes.

Pagasa weather forecaster Salvador Javier said the LPA is positioned to move out of the country and they have not monitored other weather disturbances that would affect the country.

For the next 24 hours, Pagasa said there would be a moderate to occasionally strong southwesterly surface windflow prevailing over Visayas and Mindanao, becoming light to moderate over the rest of the country.

Southern Luzon and Mindanao is expected to experience mostly cloudy skies with scattered rainshowers and thunderstorms. The rest of the country would be partly cloudy to cloudy with isolated rainshowers and thunderstorms, mostly in the afternoon or at night. – With Rhodina Villanueva, Nestor Etolle