Tropical storm "Fabian" (international name "In-fa") has maintained its strength while moving slowly over the Philippine Sea on Sunday morning, July 18, said the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

As of 10 a.m., the center of Fabian was estimated at 1,100 kilometers east-northeast of extreme northern Luzon.

It was packing maximum sustained winds of 65 kilometers per hour (kph) near the center and gustiness of up to 80 kph.

PAGASA said the cyclone may become a severe tropical storm by Monday afternoon, July 19, and further into a typhoon by Tuesday evening, July 20.

PAGASA also continues to monitor a low pressure area outside the country's area of responsibility, or at 740 km west of Basco, Batanes on Sunday morning.

Both weather disturbances are expected to strengthen the impact of the habagat over the country, PAGASA said.

As such, scattered to widespread moderate to at times heavy monsoon rains may prevail over Palawan, Occidental Mindoro, Zambales, and Bataan within 24 hours.

Metro Manila and the rest of the country are also likely to experience scattered light to moderate to at times heavy rain showers and thunderstorms.

PAGASA warned against possible flash floods or rain-induced landslides during heavy or prolonged rainfall, particularly in areas that are highly susceptible to these hazards.

"Fabian will remain far from the Philippine landmass throughout the forecast period. The tropical cyclone will maintain a north-northwestward and exit the Philippine area of responsibility (PAR) on Monday evening or Tuesday morning," PAGASA said.

While outside the PAR, PAGASA said Fabian will move west-northwestward on Tuesday and generally westward throughout the remainder of the forecast period.