A climatological analysis of the monsoon break following the summer monsoon onset over Luzon Island, Philippines

This study investigates the climatology of monsoon break following onset summer rainy season over Luzon Island (120–122.5°E, 13–22°N) in Philippines from 1979–2017. The first post-onset is remarkable stations located north and central occurs climatologically early June. Composite analysis large-scale circulation features during period shows that this associated with westward extension western North Pacific Subtropical High (WNPSH), which weakened southwesterlies induced enhanced low-level divergence Island. WNPSH may be facilitated by phase change boreal intraseasonal oscillation (BSISO). About 59% (23/39) cases occurred when suppressed convection, dry phases BSISO, apparent Pacific. convection favours expansion WNPSH. With occurrence summer, seasonal march can divided into three phases: (1) phase, between mid to late May under influence westerly/southwesterly winds, (2) rainfall decreases June, (3) revival increases again due intrusion Philippines. highlights complex impact on local climate summer.