MANILA— Super Typhoon Rosal has slightly weakened while moving northwestward over the Philippine Sea east of Batanes, with gale-force winds threatening parts of Northern Luzon, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said Thursday.

In its 5 a.m. bulletin, PAGASA located the typhoon’s center 495 kilometers east of Basco, Batanes, at 4 a.m. on Oct. 22.

Rosal has maximum sustained winds of 195 kilometers per hour near the center, gusts of up to 240 kph, and a central pressure of 915 hectopascals. It is moving northwestward at 20 kph, with strong to typhoon-force winds extending up to 780 kilometers from its center.

Tropical Cyclone Wind Signal No. 2, warning of gale-force winds of 62 to 88 kph, is in effect over Batanes and the northeastern portion of the Babuyan Islands. The warning indicates a minor to moderate threat to life and property, with a 24-hour lead time.

Signal No. 1, which covers strong winds of 39 to 61 kph and carries a 36-hour warning lead time, has been raised over the rest of the Babuyan Islands, mainland Cagayan, the eastern portion of Isabela, Ilocos Norte and Apayao.

The affected eastern Isabela localities are Maconacon, Divilacan, Palanan, Santa Maria, Cabagan, Delfin Albano, Santo Tomas, Tumauini, San Pablo, Ilagan City, San Mariano and Dinapigue.

PAGASA said Wind Signal No. 3 may be raised over Batanes as Rosal passes, although this is less likely if the typhoon follows a more north-northwestward track.

The agency also warned that the northeast wind flow and Rosal’s outer circulation would bring strong to gale-force gusts to most of Luzon and Visayas on Thursday, as well as Zamboanga del Norte, Northern Mindanao, Agusan del Norte, Surigao del Norte, Dinagat Islands, Sarangani, Davao Occidental and Davao Oriental.

Similar gusts are expected over most of Luzon and Visayas, Davao Occidental and Davao Oriental on Friday. By Saturday, affected areas are expected to include Batanes, the Babuyan Islands, Ilocos Norte, the Polillo Islands, Bicol Region, Romblon, Capiz, Iloilo and Negros Occidental.

A gale warning is in effect over the northern and eastern seaboards of Luzon, with waves reaching up to 12 meters along the northern and eastern coasts of Batanes within the next 24 hours.

Waves may reach up to nine meters along the remaining coasts of Batanes, the Babuyan Islands and the northeastern coast of mainland Cagayan. Other coastal areas of Cagayan, Isabela and parts of Northern Luzon are also expected to experience very rough to very high seas.

PAGASA warned that sea travel would be dangerous for all types and tonnage of vessels in areas facing these conditions. Mariners were advised to remain in port or seek shelter in a safe harbor if already at sea until winds and waves subside.

Small vessels, including motorbancas, were also advised against venturing out into rough seas, while operators in areas with moderate to rough conditions were urged to take precautions and avoid sailing if possible.

Rosal is expected to continue moving northwestward until Friday morning before turning north-northwestward Friday afternoon and recurving north-northeastward on Saturday. On its forecast track, the typhoon will be closest to Extreme Northern Luzon between Thursday afternoon and Friday morning.

The cyclone is expected to exit the Philippine Area of Responsibility by Friday evening or early Saturday.

PAGASA said Rosal would continue to gradually weaken and could be downgraded to a typhoon within Thursday. By Saturday, it is expected to weaken more rapidly and may be downgraded to a severe tropical storm.

The agency stressed that heavy rainfall and strong winds may still affect areas outside the forecast track and confidence cone, and that the projected path could still change.

The public and concerned disaster risk reduction and management offices were advised to take necessary measures to protect lives and property. Residents in areas highly or very highly susceptible to hazards were urged to follow evacuation orders and other instructions from local officials.

PAGASA said its next tropical cyclone bulletin would be issued at 11 a.m. Thursday.