Tropical Cyclone Wind Signal (TCWS) Number One was hoisted in some parts of Luzon as ''Siony'' intensified into a severe tropical storm, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said on Wednesday.

In its latest bulletin, Pagasa said Siony was last spotted at 735 east of Basco, Batanes with winds of up to 95 kph and gusts of up to 115 kph.

''Siony'' is slowly moving towards north and is also forecast to remain almost stationary in the next six to 12 hours before moving westward or west-northwestward towards the Luzon Strait and extreme Northern Luzon.

Pagasa said the eye of the storm will be over or very close to the Batanes and Babuyan Islands between Thursday evening and Friday morning.

“As such, a landfall scenario over these localities remains likely… It is forecast to intensify into a typhoon prior to its landfall or close approach over extreme Northern Luzon and may reach its peak intensity of 125 kph,” it said.

Pagasa raised the warning signal over the northeastern portion of mainland Cagayan (Santa Ana, Gonzaga) and the eastern portion of Babuyan Islands (Balintang Island, Babuyan Island, Didicas Island, and Camiguin Island including their adjoining islets).

The weather bureau said ''Siony'' is expected to leave the Philippine Area of Responsibility (PAR) by Friday afternoon or evening. Ella Dionisio/DMS