The center of extremely powerful Typhoon Meranti moved closer to the southern end of Taiwan during the past few hours. At 5:00 p.m. EDT on Tuesday the center of Typhoon Meranti was located at latitude 21.1°N and longitude 121.3°E which put it about 65 miles (105 km) south-southeast of Hengchun, Taiwan. Meranti was moving toward the west-northwest at 11 m.p.h. (18 km/h). The maximum sustained wind speed was 190 m.p.h. (305 km/h) and there were wind gusts to 230 m.p.h. (370 km/h). The minimum surface pressure was 887 mb.
Typhoon Meranti is large and powerful. The Hurricane Intensity Index (HII) is 46.1. The Hurricane Size Index (HSI) is 27.9 and the Hurricane Wind Intensity Size Index (HWISI) is 74.0. As a source of comparison, when Hurriane Katrina was at its peak intensity as a Category 5 hurricane over the Gulf of Mexico in 2005, its HII was 38.6, its HSI was 33.7, and its HWISI was 72.3. Typhoon Meranti is stronger than Hurricane Katrina was, but Meranti is a little smaller than Katrina was in 2005. The indices suggest that Typhoon Meranti is capable of causing widespread catastrophic damage.
The circulation of Typhoon Meranti is symmetrical and very well organized. It possess a tight core consisting of a small inner eye surrounded by a ring of very tall thunderstorms. A second, larger outer eyewall completely surrounds the inner eye. The strongest winds are occurring in the inner eyewall near the center of circulation. Winds to typhoon force are also occurring in the outer eyewall and extend out at least 80 miles (130 km) from the center of circulation. Additional bands of strong thunderstorms are rotating around the outer eyewall. Typhoon Meranti is generating strong upper level divergence which is pumping out large quantities of mass and is allowing the surface pressure to be so low.
Typhoon Meranti is probably at its peak intensity. It is still moving over water where the Sea Surface Temperature is near 31°C. However, the northwestern edge of the outer eyewall appears to be moving over the southern end of Taiwan. As more of the circulation moves over Taiwan, there will be some disruption of the airflow. The center of Typhoon Meranti could move very close to the southern tip of Taiwan. If the center of Meranti moves over southern Taiwan, then the typhoon will weaken more quickly. It currently appears that the center of Typhoon Meranti could move just south of the southern tip of Taiwan, and on that track the typhoon would not weaken as quickly. When Typhoon Meranti moves west of Taiwan, it will move over slightly cooler SSTs before it reaches China. Meranti will weaken more before it reaches China, but it will still be a significant typhoon when it makes landfall there.
The center of Typhoon Meranti is wobbling a little as the inner eye rotates around inside the outer eyewall. If one averages the wobbles, then then core of Meranti is moving on a general west-northwesterly track. On its anticipated track, the center of Typhoon Meranti will pass very near the southern end of Taiwan during the next few hours. It could turn slightly toward the northwest as it moves west of Taiwan. Typhoon Meranti could make a landfall on the coast of China between Xiamen and Shantou in about 24 hours.
Typhoon Meranti is an extremely dangerous storm. It is capable of causing widespread catastrophic wind damage. In addition, its intensity and size will produce very heavy rainfall, especially on the eastern slopes of the mountains on Taiwan. Flash flooding is likely. Typhoon Meranti will also produce heavy rain over eastern China and additional flooding is likely in that region. Typhoon Meranti will also cause a significant storm surge in low lying coastal areas.