MANILA — The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) on Monday warned of possible heavy rainfall in several provinces due to the Southwest Monsoon (Habagat) through Wednesday, August 19. In Weather Advisory No. 62 issued at 5 a.m., PAGASA forecast 50 to 100 millimeters of rainfall today in Ilocos Sur, La Union, Pangasinan,…