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Only one Doppler radar in Mindanao – PAGASA
PAGASA has only one rainfall-and-storm tracking Doppler radar located in Mindanao, where Tropical Storm ‘Sendong’ (international codename: Washi) cut a path of destruction—leaving possibly over 600 dead. That lone Doppler is in Hinatuan, Surigao del Sur in the Northeastern section of Mindanao called Caraga. The whole island is rarely visited by storms. In fact, the last storm to take approximately the same path as Sendong was ‘Tonyo’ a little over three years ago in November 2008. PAGASA officials have said that the current five Doppler radar facilities are not enough to give PAGASA accurate forecasts. The other four are in Tagaytay, Subic, Baguio City, and Baler in Aurora province. The radars have a coverage range of 480 kilometers. Some radars also have blind spots due to mountain ranges and other obstructions, making them unable to monitor some areas. PAGASA stands for Philippine Atmospheric, Geophysical and Astronomical Services Administration. NASA forecast 'severe flooding' Just before ‘Sendong’ made landfall on Mindanao, the United States’ National Aeronautics and Space Administration (NASA) had its Tropical Rainfall Measuring Mission (TRMM) satellite pass over the storm for a detailed scan. NASA overlaid data from its TRMM Microwave Imager (TMI) and Precipitation Radar (PR) on an enhanced infrared image from the satellite's Visible and InfraRed Scanner (VIRS). The resulting rainfall analysis showed that “Washi was much better organized with very heavy rainfall of over 50mm/hr (~2 inches) revealed by TRMM PR within bands spiraling into the center of the storm." NASA forecast severe flood potential over many cities and towns in Mindanao. For example, rainfall on Iligan was seen ranging from 149 to 294 millimeters (mm) while over Cagayan de Oro the projection was from 130 mm to 218 mm. Late evening of December 15 (11 p.m.), when it became clear to PAGASA that ‘Sendong’ was taking a westward path to Misamis instead of northwest to the Eastern Visayas provinces, the weather bureau’s estimated rainfall was 10 – 25 mm per hour over the 400-kilometer diameter or span of Sendong. That same evening, Storm Signal No. 2 was raised over the Misamis provinces and other parts of Northern and Western Mindanao. But at that time, Sendong was still far from Cagayan de Oro and Iligan because it had not yet made landfall on eastern Mindanao. According to standard operating procedure of the National Disaster Risk Reduction and Management Council, the PAGASA severe weather bulletin was cascaded down to its field offices and local government units. But with the exception of Caraga, Mindanao is unaccustomed to storms. PAGASA explained on its website that storms that enter the Philippine area of responsibility usually form in the western Pacific then “follow a northwesterly direction, sparing Mindanao from being directly hit by majority of the typhoons that cross the country.” 'At risk' areas 'Sendong' did not spare Northern Mindanao and its rain-filled clouds fell on the highlands of Bukidnon, as well as the coast and inland of Misamis Oriental and Misamis Occidental. These provinces happen to have many rivers and streams, which have been clearly mapped by the National Mapping and Resource Information Agency (NAMRIA). Another NAMRIA map also identifies the coasts of the Misamis provinces, Cagayan de Oro City and Pagadian City as areas vulnerable to the phenomenon of sea level rise.
