MANILA (2nd UPDATE) - As much as 600 millimeters of rain fell on Manila Bay on August 18, a new record high, according to scientists.
The record-high rains were spawned by the southwest monsoon, or habagat, intensified by storm Maring.
Project NOAH's Dr. Mahar Lagmay on early Monday morning shared Doppler radar maps created by the University of the Philippines-National Institute of Geological Sciences' Irene Crisologo that showed the extent of rainfall in Metro Manila and nearby areas Sunday and Monday.
The accumulation maps show areas in Cavite, Pampanga, Bataan, Zambales and Manila Bay covered in pink (420 mm to 580 mm rainfall), as well as white (600 mm or almost two feet of rain).
To compare, Ondoy dumped only around 455 mm rainfall in 24 hours in 2009, and around 472 mm of rainfall fell in Quezon City in a day during the 2012 habagat.
The 600 mm amount of rain seen on the August 18 Doppler radar map did not fall over land, but over Manila Bay.
"There is a blind spot sa radar. Nasa south sector. Madami ang ulan na bumagsak sa Manila Bay. Iyung matataas ay sa Manila Bay," Lagmay told ABS-CBNNews.com.
"For the white areas (600 mm rainfall) , there are currently no rain gauges that would verify those readings," Crisologo said.
Lagmay echoed her statement. "Noong habagat 2012 ay ganyan din. Sa dagat (lang) bumagsak," he said.
The two UP NIGS scientists said the Doppler radar map is consistent with the latest data from the Manila Observatory on Metro Manila that shows the southern parts of the metropolis getting more than 250 mm rainfall in less than 24 hours Sunday and Monday.
Data from the observatory, an independent weather research institute based at the Ateneo de Manila University, shows that hardest-hit areas in Metro Manila are the cities of Las Piñas, Parañaque, and Makati.
Accumulated rainfall from 9 pm Sunday to 6 pm Monday in Las Piñas reached more than 250 mm, with the peak of more than 50 mm recorded around 4 am Monday.
Kabihasnan in Paranaque got more than 200 mm rainfall during the same period; Guadalupe in Makati City got around 160 mm, according to Manila Observatory data.
It said Ondoy rainfall amount it recorded in Loyola Heights, Quezon City, reached 370 millimeters in September 2009.
It added that during the habagat rains last year, around 250 mm rainfall was recorded August 7 at Loyola Heights.
From 12 am on August 18 this year to 6 pm August 19, more than 250 mm rain fell on both Las Piñas and Sucat, Parañaque.
Swamped by floods
In Metro Manila on Monday, people were forced to go to their rooftops while others were forced to swim in floodwaters in scenes eerily reminiscent of "Ondoy" and last year's habagat.
The flooding that hit Metro Manila and nearby provinces was caused by monsoon rains, enhanced by Tropical Storm Maring.
"Bukas meron pa rin tayong ine-expect na rainshowers and thunderstorms, lalo na sa hapon at gabi, and by Wednesday gradually mag-iimprove ang weather condition natin," PAGASA officer Esperanza Cayanan said Monday.
The floods forced the cancellation of classes, government offices, and courts.
Manila's City Hall wasn't spared.
Manila Mayor Joseph Estrada blamed the flooding in the city on garbage blocking the drainage system and illegal settlers.
At least three people were reported killed, while nearly 20-thousand families were affected.
Executive Secretary Paquito Ochoa advised the public to stay indoors.
"Iwasan muna magbiyahe at this time, dahil even if the amount of rainfall we're getting according to PAGASA is less than yesterday, still it doesn't mean na yung pagbabaha ay immediately humihina," he said in a press briefing.
"Maging vigilant pa rin mga tao natin, mga mamamayan natin, yung mga nasa evacuation centers mas maganda siguro mag-stay muna kayo dyan, wag muna kayo bumalik hanggat walang sapat na clearance yung mga lugar ninyo," he added.
Various government agencies have been mobilized to bring help to those affected by floods.
