Nowcasting Of Southwest Monsoon Rainfall In Metro-Manila

Ninio Alejandre Relox, Sharon Juliet M. Arruejoa

Initial study towards the development of nowcasting scheme of rainfall in Metro Manila was conducted using rainfall observation in three weather stations located South to Southwest of the study area, namely: Iloilo, Puerto Princesa and Coron. The procedure which was adapted is similar to the Early Warning System (EWS) for flood although this initiative was based on the assumption that the amount of rain observed at three stations will be equal to the rain rate in Port Area.

Analysis show that real time rainfall in Iloilo, Coron and Puerto Princesa, gave similar pattern with Port Area rainfall which is lag 24-, 96-, and 72-hours, respectively although with deviations in some cases. The amount, however, are not equal. Correlation coefficients of the test data also confirm the graphical result. Despite the fact that the rainfall observation in three identified stations is not reliable for nowcasting rainfall in Metro Manila the method used still shows great potential and can be improved by establishing a rainfall station close to and in front of where the monsoon wind is passing before it reaches Metro Manila.

It is therefore recommended that a follow-up study be conducted by establishing a rainfall observation station at the Southwest of Lubang Island which will serve as Early Warning Site of rainfall for Metro Manila.