Patterns and drivers of heavy and extreme hourly rainfall events over Metro Manila, Philippines

This study investigates the spatio-temporal characteristics of heavy hourly rainfall (HHR; 95th–99th percentile) and extreme hourly rainfall (EHR; >99th percentile) events over Metro Manila, Philippines, and quantifies the percentage contributions of synoptic scale (Tropical Cyclones (TCs) and Low Pressure Systems (LPSs; weaker disturbances than TCs)) and local scale systems (convective and stratiform rainfall events) to the total HHR and EHR, during the southwest monsoon season from 2012 to 2019. The results show higher mean rainfall intensities for both HHR and EHR events in stations located further inland and close to mountainous areas. An evident afternoon peak is observed for both HHR and EHR events possibly caused by the diurnal heating over land. A secondary peak is also observed in the early morning hours for HHR events, which is likely caused by the convergence between the local wind circulations and the prevailing monsoon southwesterlies. Both HHR and EHR events are dominated by short–duration events (1–2 h) (HHR: 69–82