MANILA — Monsoon rains are expected over parts of northern and central Luzon on Saturday as the southwest monsoon continues to affect Luzon and the Visayas, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said. In its 4 a.m. forecast, PAGASA said a low pressure area (LPA) was located 520 kilometers north-northeast of Itbayat,…