Yancy moved erratically as it skirted along the northern coastline of Taiwan and made a subsequent landfall in southeastern China, where it lingered for several days before dissipating on August 23.

In Taiwan, torrential rainfall ruined 9,900 ha (24,400 acres) of crops, caused landslides that disrupted travel, damaged houses, downed trees, and cut power to 525,000 families.

At 06:00 UTC on August 9, Yancy was first noted by the Joint Typhoon Warning Center (JTWC) in a Significant Tropical Weather Advisory as an area of persistent convection.

[nb 1] What would eventually develop into Typhoon Yancy initially began as a low-level convective center on the eastern side of a monsoon depression.

[3][nb 2] Of the aforementioned TCFAs, the first was issued at 21:00 UTC on August 11 based on the improving state of the disturbance's central convection and upper-level outflow coupled with decreasing barometric pressure at multiple nearby stations on land.

A second alert was issued at 14:00 UTC the following day in response to a northward shift of a low-level center and further decreases in surface pressure.

[2][5] Yancy's trajectory shifted from westward to north-northwestward after the subtropical ridge weakened in response to a shortwave trough moving off the coast of China.

According to JTWC data, Yancy intensified into the equivalent of a Category 2 on the Saffir–Simpson scale at 18:00 UTC on August 17, peaking in intensity six hours later with one-minute sustained winds of 90 knots (165 km/h; 105 mph).

[2][5] JMA data, however, placed Yancy's peak intensity eighteen hours later, with ten-minute sustained winds of 80 knots (150 km/h; 90 mph) and a minimum barometric pressure of 28.05 inHg (950 mbar).

[2] The JMA similarly found that Yancy had weakened to a tropical depression on August 22, and it stopped tracking the system the next day.

[3] In the Philippines where Yancy was known by the PAGASA name "Gading",[6][nb 3], a monsoon surge triggered by the storm resulted in significant rainfall which flooded areas across northern Luzon.

The hardest hit locale was Wenzhou, where approximately 99,000 ha (240,000 acres) of land suffered extensive flooding,[8] and where grain losses amounted to 20,000 tons.

[20] In eastern Guangdong, the effects of the storm, chiefly from heavy rainfall, collapsed 4,800 homes and inundated about 89,000 ha (220,000 acres) of farmland.