The state weather bureau predicts rainshowers and thunderstorms over parts of Luzon and Visayas on Wednesday due to the effects of the “monsoon trough” over southern Luzon.
In his report on the weather forecast for the next 24 hours issued at 5 p.m. on Tuesday, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) forecaster Benison Estareja said the “prevailing weather system” was that of the monsoon trough, as no low pressure area or tropical cyclone has been spotted in the Philippine area of responsibility.
According to the American Meteorological Society online glossary, a “monsoon trough” is “the line in a weather map showing the locations of relatively minimum sea level pressure in a monsoon region.”
Heavy monsoon rains are associated with monsoon troughs as “most of the active transient disturbances producing the monsoon rain develop and move along the monsoon trough region.”