TAIPEI (Taiwan News) — Tropical storms Francisco and Co-may are exhibiting signs of the Fujiwhara effect as they rotate counterclockwise around each other, likely bringing heavy rain and strong winds to northern and northeastern Taiwan.
As of 2 a.m., Francisco was located 710 kilometers east-southeast of Taipei, moving northwest to west-northwest at 20 kph, per CNA. Co-may was 630 kilometers south-southwest of Eluanbi, moving east-southeast to northeast at 11–14 kph.
Meteorologist Daniel Wu (吳德榮) said the outer circulation of Francisco, along with the monsoon, will bring significant rainfall and strong gusts to the north and northeast on Thursday. Central and southern Taiwan may also see scattered afternoon showers or thunderstorms.
From Friday to Sunday, the combined effects of Francisco, Co-may, and the monsoon will bring rain and gusty winds to areas north of central Taiwan. Southern Taiwan will continue to see a chance of isolated thunderstorms.
The Central Weather Administration expects Francisco to pass east of Taiwan and enter northern coastal waters, though its structure remains weak. Co-may, located northwest of Luzon, is forecast to turn northeast and weaken as it crosses the island.
The two systems are being steered by the monsoon and are showing signs of Fujiwhara interaction, in which two tropical storms spin around a common point and influence each other’s movement. Wu said this interaction is contributing to their erratic paths.
He added that a third tropical system is developing over waters north of Guam. It is expected to intensify but will likely track northward without affecting Taiwan.
From Monday to Wednesday, the monsoon will continue to destabilize the atmosphere, bringing a chance of localized showers nationwide. Strong afternoon convection could trigger lightning, gusty winds, and sudden downpours, while non-rainy periods will remain hot and humid.
