TROPICAL Storm Nika, moving west at 35 kilometers per hour (kph), is expected to gradually intensify into a severe tropical storm before landfall over Isabela or Aurora on Monday afternoon or evening, the state-run weather bureau said Saturday.

In its 5 p.m. bulletin, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) noted that the storm's center was estimated at 1,005 kilometers east of Southeastern Luzon with maximum sustained winds at 65 kph near the center and gustiness of 80 kph.