Siony is forecast to move slowly or remain almost stationary in the next 12 hours. Afterward, the tropical storm will move generally westward or west-northwestward towards the Luzon Strait and Extreme Northern Luzon.
This will bring the center of Siony over or very close to the Batanes and Babuyan Islands between tomorrow evening and Friday morning. As such, a landfall scenario over these localities remains likely. On the forecast track, Siony will leave the Philippine Area of Responsibility on Friday afternoon or evening.
Siony is forecast to intensify into a severe tropical storm in the next 24 hours and reach its peak intensity of 100-110 km/h tomorrow prior to its landfall or close approach over Extreme Northern Luzon. However, intensification into the typhoon category is not ruled out at this time.
In the next 24 hours, the northeasterlies enhanced by Tropical Storms “ROLLY” and “SIONY” 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.
In anticipation of strong breeze to near gale conditions associated with the tropical storm, Tropical Cyclone Wind Signal #1 is now in effect for several areas in Extreme Northern Luzon. Based on all available meteorological data, the highest wind signal to be raised will be TCWS #2.
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Siony continues to move slowly over Extreme Northern Luzon
However, because intensification into typhoon category remains a potential scenario at this time, the possibility of hoisting TCWS #3 in areas near or along the projected track of the storm is not ruled out.
The combined effects of the northeasterlies and the trough of “SIONY” will bring light to moderate with at times heavy rains over Aurora, Quezon, Camarines Norte, Camarines Sur, Catanduanes, and the eastern portions of Cagayan and Isabela.
Flooding (including flashfloods) and rain-induced landslides may occur during heavy or prolonged rainfall especially in areas that are highly or very highly susceptible to these hazards and/or those that received significant antecedent rainfall from tropical cyclones “PEPITO”, “QUINTA”, and “ROLLY”.
PAGASA Regional Services Divisions may issue local thunderstorm/rainfall advisories and heavy rainfall warnings as appropriate.