Storm Signal No. 2 could be raised over Ilocos Norte in the next three days after weather forecasters expected “Pepeng,” which weakened into a tropical storm Monday, to stay “almost stationery” over South China Sea after it was pulled back by Typhoon “Quedan” which entered the country Monday.

Nathaniel Cruz, director of Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), said Tropical Storm “Pepeng” will likely hover in the northeastern part of the South China Sea at around 230 kilometers north northwest of Laoag City until Wednesday, exposing Ilocos region to more heavy rains and strong winds in the next 48 hours.

In a press briefing, Cruz explained that the entry of Typhoon “Quedan” in the country as of 11 a.m. on Monday pulled Pepeng back, prolonging its stay within the Philippine area of responsibility (PAR) instead of going near the vicinity Hong Kong early this week.

“This is what we call the Fujiwara effect, (where) there is a fulcrum or axis that when one tropical cyclone moves (one) way, the other one goes the opposite way. We are experiencing a dumbel effect,” Cruz told reporters.

The Fujiwara effect is a type of interaction between two eyes of tropical cyclones, causing them to appear to “orbit” each other. When the cyclones approach each other, their centers will begin orbiting cyclonically about a point between the two systems.

In the meteorological event, the two vortices will be attracted to each other. However, when the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex would orbit around it.

As of 11 a.m. on Monday, PAGASA monitored Quedan over the Philippine Sea at about 1,220 kilometers east of Northern Luzon, packing maximum sustained winds of 205 kph near the center and a gustiness of 250 kph.

“This typhoon is stronger than Pepeng,” Cruz noted, explaining that the new typhoon also weakened Pepeng, which packed 95 kph maximum sustained winds near the center and gustiness of up to 120 kph as of Monday noon.

Meanwhile, PAGASA senior weather forecaster Robert Sawi said that Quedan has been moving west northwest towards the southern part of Japan in Okinawa, causing Pepeng to stay in a quasi stationary status along the South China Sea.

“With the coming of Typhoon 'Quedan,' we expect 'Pepeng' to either follow a re-curved movement towards northeast tailing 'Quedan' towards Okinawa, Japan, or to move away from South China Sea towards Vietnam after 48 hours,” Sawi told a press briefing.

“It will most likely not make landfall again in Northern Luzon,” he said, clarifying that the storm will certainly affect the weather in Ilocos, Cagayan, and Cordillera provinces.

Cruz added that the ridge of High Pressure Area (HPA) near Hong Kong also contributed to the continuing weakening state of Pepeng that could also influence the track of four-day old disturbance towards Vietnam by 50 percent.

The PAGASA spokesperson said that because of this, Storm Signal No. 1 will most likely be  maintained over Ilocos Sur, Apayao, Batanes group of islands, Northern Cagayan, including Calayan and Babuyan group of islands.

He warned that residents along the western coast of the Ilocos region to “stay on alert” for storm surges that will be brought by the Tropical Storm for the next two days. But he assured that rains along these areas will be a bit more relaxed compared to the heavy amount of rainfall in the last few days.

He added that the Cagayan and Cordillera provinces will have lesser rains and weaker gust of winds while Central and Southern Luzon, including Metro Manila, will experience an improved weather in the next three days.