MANILA— Tropical Storm Siony has maintained its strength over the Philippine Sea, weather bureau PAGASA said Tuesday night, while Tropical Storm Rolly left the Philippine Area of Responsibility (PAR) after devastating parts of Luzon over the weekend.

Siony was packing maximum sustained wind speeds of 85 kilometers per hour (kph), with gusts of up to 105 kph, the national weather agency said in its 11 p.m. bulletin. It was last spotted 665 kilometers east of Basco, Batanes.

PAGASA said Siony was forecast to intensify into a severe tropical storm in the next 24 to 36 hours, and may reach peak intensity at 100 to 110 kph on Thursday prior to its landfall over extreme northern Luzon.

“This will bring the center of "Siony" over or very close to the Batanes and Babuyan Island between Thursday evening and Friday morning. As such, a landfall scenario over these localities remains likely,” it said.

Siony, however, is moving slowly "in an apparent looping manner or remain almost stationary" within the next 24 hours, PAGASA added.

In the next 24 hours, the northeasterlies enhanced by both Siony and Rolly will bring strong breeze to gale-force winds with higher gusts over Batanes, Babuyan Islands, and the northern coastal areas of Cagayan and Ilocos Norte.

PAGASA also said it may raise Tropical Cyclone Wind Signal No. 1 over some provinces in Cagayan Valley by Wednesday in anticipation of the strong breeze to near gale conditions associated with Siony.

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Meanwhile, Tropical Storm Rolly, which made landfall as a super typhoon then weakened on its way across parts of southern Luzon Sunday leaving at least 19 people dead, is now outside the PAR.

PAGASA said Rolly left the PAR at 8 p.m. It is forecast to move over the West Philippine Sea towards the southern part of Vietnam.

PAGASA said the tropical cyclone, by far the world’s strongest storm this year, was last seen 615 kilometers west of Subic, Zambales, packing maximum sustained winds of 75 kph and gustiness of up to 90 kph.

The agency said the combined effects of Rolly and Siony, as well as the enhanced northeasterlies, will bring rough to very rough seas, with waves from 2.8 meters to 5 meters, over the entire seaboards of Northern Luzon and the seaboards of Kalayaan Islands.

Sea travel is risky over these waters, especially for those using small seacraft.

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