Total rainfall in the southeast Philippines from January 10-17, 2014. NASA-TRMM image
MANILA (UPDATED) - Rain dumped by tropical depression Agaton in northeastern Mindanao for a week more than doubled the volume of rain that tropical storm Ondoy brought for 24 hours in Metro Manila in 2009, according to the US National Aeronautics and Space Administration's satellite data.
NASA's Global Precipitation Measurement and Tropical Rainfall Measuring Mission said more than 1,168 mm (about 46 inches) of rain fell in northeastern Mindanao from January 10 to 17 this year amid the low-pressure area in the region that later developed into tropical cyclone Agaton.
It described the Agaton's rainfall volume as "extremely high."
To compare, storm Ondoy dumped around 455 mm rain in Metro Manila in 24 hours.
NASA's satellites found rain falling at a rate of over 154 mm per hour in "strong convective storms" off the northeastern coast of Mindanao during the height of Agaton's passage in the region.
Again comparing with Ondoy, the 2009 storm delivered over 300 mm of rain in 6 hours at its height, or an average of 50 mm per hour.
The soil can absorb only between 40–60 mm in 6 hours without flooding, according to scientists.
"People in the southern Philippines are used to heavy rainfall this time of the year but rainfall totals have recently been exceptionally high," NASA said.
NASA's TRMM is providing updated data on rainfall amounts, flood inundation calculations, landslide potential maps in its website.
Results are shown at its Global Flood and Landslide Monitoring web pages.
The Ateneo de Manila University-based Manila Observatory also said 9 days worth of continuous rain have fallen in parts of Mindanao.
Most of the affected areas got about a month's worth of rain in just 3 days, it added.
At least 42 dead, 360,000 displaced
Agaton has now killed at least 42 people and left 7 others missing, according to the National Disaster Risk Reduction and Management Council (NDRRMC).
It has also displaced more than 360,000 people in the southern Philippines and directly affected almost 800,000 people in 15 provinces in 4 regions.
State weather bureau PAGASA warned that although Agaton has been downgraded back into a low-pressure area, it will still bring moderate to heavy rains and thunderstorms over Northern Mindanao, Caraga, and the Davao Region.