Why does extreme precipitation occur in the Philippines during El Niño winters?

As an archipelagic nation, the Philippines is highly vulnerable to the adverse impacts of weather-related hazards, such as extreme precipitation events. Despite the typical dry conditions associated with the warm phase of the El Niño-Southern Oscillation (ENSO) in the tropical Pacific Ocean, extreme precipitation days still occur in the Philippines during boreal winters. This paradoxical occurrence of extreme precipitation days during the typically dry conditions associated with the warm phase of ENSO underscores the complexity of the processes leading to extreme precipitation in this region. It is important to comprehensively understand the mechanisms driving extreme precipitation in the Philippines. In this talk, we will present an analysis of boreal winter extreme precipitation over the Philippines and its associated circulation features from the synoptic scale to the sub-seasonal scale. It is found that tropical cyclones and depressions play a crucial role in resulting in extreme precipitation days in the Philippines during ENSO winters. The tracks of tropical cyclones and depressions show different characteristics in extreme precipitation days between El Niño and La Niña winters. The physical explanation will be provided for the above features based on observational analysis. A parallel analysis for weak precipitation days in the Philippines will be conducted to help understand the conditions for different precipitation events.