TS Siony’s ‘erratic’ track makes predictions uncertain; Pagasa carefully watches

MANILA, Philippines — State meteorologists were closely monitoring the track of Tropical Storm Siony (international name: Atsani) as local predictions have a high degree of uncertainty, the Philippine Atmospheric, Geophysical and Astronomical Services (Pagasa) said Monday.

According to Pagasa’s latest bulletin, Siony was last seen 665 kilometers east of Calayan, Cagayan, packing maximum sustained winds of 65 kilometers per hour (kph) and gustiness of up to 80 kph.

While it is currently moving north at a speed of 25 kph, Pagasa said it expects Siony’s behavior to be “erratic” and make a loop while hovering over the sea in the next two days due to two high-pressure systems pushing it.

The state weather bureau also said it has a broad “cone of probability” for Siony’s path that it is likewise likely that the tropical storm will strengthen into a severe tropical storm as it approaches extreme northern Luzon and will become a typhoon as it crosses the area.

“Magiging erratic naman ang inaasahan na pagkilos ni Tropical Storm Siony, ‘yan po ay nandyan pa rin sa gitna ng karagatan in the next two days kung saan siya posibleng umikot or magloop, at ‘yan po ay dahil sa dalawang high pressure system na tutulak sa kanya,” weather specialist Ariel Rojas noted.

“Mapapansin din natin na malaki po ang ating cone of probability kung saan posibleng pumunta itong si Tropical Storm Siony so habang papalapit po ‘yan dyan sa may extreme northern Luzon, ang bagyo po from tropical storm ay posibleng lumakas into severe tropical storms at habang tumatawid ay posibleng maging typhoon,” he added.

For now, Siony is predicted to stay almost stationary moving northward and then shift to the east by Tuesday, turn south on Wednesday, and then complete a loop by moving southeast before Thursday prior to either moving extreme north or going southward to hit Central Luzon, according to Pagasa.

At present, Pagasa also has not raised any tropical cyclone wind signals due to Siony.

As for Rolly, which battered Southern Luzon as a tropical storm on Sunday morning before gradually weakening into a typhoon, it is expected to leave the country by Tuesday morning. Now already packing maximum sustained winds of 65 kph and gustiness of 80 kph, Rolly was last spotted 225 kilometers west of Iba, Zambales. It was moving north-northwest at 15 kph, the state weather bureau said.

Tuesday weather in Luzon will be cloudy and drizzly due to the trough of Rolly and Siony, according to Pagasa, with Metro Manila and Legazpi City residents likely to experience temperatures between 25°C and 31°C while Tuguegarao and Laoag residents may have it from 23°C to 31°C and 25°C to 30°C, respectively.

Precipitation is also probable over the western parts of Visayas and Mindanao, but the rest of the regions will have generally fair weather as temperatures between 24°C and 32°C were forecast for Cebu City, 25°C and 31°C for Tacloban, 25°C and 32°C for Davao City, and 23°C and 33°C for Cagayan de Oro City.

And even if Rolly has been moving away from the Philippine area of responsibility, Pagaisa maintained its gale warning over the entire northern seaboards of Luzon, as well as in the coastlines of Ilocos Region, Cagayan, and Isabela.

KGA