(UPDATE) The rainfall caused by the southwest monsoon in Metro Manila is almost as devastating to the volume of rain in the 2009 typhoon Ondoy, an official on Tuesday said.
Accumulated rainfall from 4:45 p.m. on Aug. 6 to 3 p.m. of Aug. 7 reached 472 millimeters monitored from the Quezon City Polytechnic University, even higher than Ondoy's accumulated 455 millimeters in 24 hours, Mahar Lagmay, who leads the inter-agency National Operational Assessment of Hazards Project (Project NOAH), said in a phone interview.
Lagmay, however, noted that a comparison cannot accurately be made as other observation posts have recorded lower rainfall levels. He also noted that Ondoy's flood peaked earlier than this monsoon.
"We also have to point out the difference in time frame. Rain due to Ondoy peaked for six hours while the rain currently caused by the monsoon is over an extended period," Lagmay said.
The weather bureau as of its 9:30 p.m. update meanwhile kept Metro Manila under a "red warning signal," noting that heavy to intense (10-25 mm/hr) with occasional to frequent torrential (over 30 mm/hr) may be expected in the next three hours.
There is no tropical storm within the Philippine area of responsibility but tropical storm Haikui located 300 kilometers northeast of Taiwan worsens the effect of the southwest monsoon, the Philippine Atmospheric Geophysical and Astronomical Services Administration (Pagasa) said.
In its weather advisory, Pagasa noted "occasional to frequent rains over Luzon becoming moderate to heavy rains" in Metro Manila and the provinces of Ilocos, La Union, Pangasinan, Tarlac, Zambales, Bataan, Pampanga, Bulacan, Rizal, Cavite, Laguna, Batangas up to Wednesday.
Gradual improvement may be expected by Thursday until the weekend.
"Expect landslides/flashfloods in mountainous areas and floods in low lying areas," Pagasa said.