The people in Taiwan are anticipating the arrival of Typhoon Finapi. Among other things, it is disrupting the fishing season that just started at the beginning of the month. Perhaps more importantly, the Typhoon is packing winds that will cause concern for damage and a potentially devastaing surge. However, the actual surge is determined by geograhpical features of the island as well as the physical features of the shelf and I am not aware of the physical features around Taiwan. I cannot find any buoys in the region that are in operating condition but reports of 28 foot seas have been made. While the forward speed of around 12 mph might limit the storm surge potential to a small degree, winds running at 105 kts (120 mph) will be sufficient to push a substantial amount of water up to the right of landfall. Typhoon Fanapi’s intensity puts it as an equivalent of a category 3 hurricane. Beyond the wind and surge threat, the topography of the island will serve to enhance rain totals and authorities are expecting up to 20 inches in some areas. With a storm travelling around 10 mph, Typhoon conditions can be expected in several parts of the island for up to 8-12 hours.
When you look at the satellite imagery, you find that Finapi is a well formed, compact tropical cyclone but the outflow to the north is almost absent while there remains some outflow to the south. There is a big fat high to the north of the cyclone that is inhibiting the poleward outflow which may have inhibited the storm from becoming even more intense. The central pressure of 935 mb has the potential to support winds higher than previous estimates. Nevertheless, tropical storm force winds extend up to 150 miles from the center and typhoon winds some 35 to 40 miles from the center of circulation. I suspect that there is the possibility that this storm may be getting slightly more intense as it approaches Taiwan for landfall as it appears that Fanapi has completed an eyewall replacement cycle. An eyewall replacement cycle is a natural occurence related to a well developed tropical cyclone and typically, the maximum winds decrease as the storm goes through the cycle of replacing an eyewall, though the overall strong windfield expands. Once the cycle is complete, then the storm returns to its previous intensity. Hence, the satellite imagery suggests that the cycle is complete and Fanapi may be ramping up toward maximum potential just prior to landfall.
For what it’s worth, Fanapi is the Micronesian name for “sandy islands” and it is expected to continue on its track generally to the west at around 10 kts and the Joint Typhoon Warning Center Forecasts points to a landfall about 70 miles SSE of Taipei near the coastal town of Hualien. Geographically speaking, it seems to me that the little bay to the north of Hualien may be vulnerable to an enhanced surge. Once the storm makes landfall, the topographical features of Taiwan will disrupt the storm sufficiently that it will fall to below 100 kts when it re-emerges over the Taiwan Straits and will move into China within 36 hours with winds of around 80 to 85 kts about 150 miles Northeast of Hong Kong. Inland flooding will be a concern for China as the storm dissipates, particularly when one considers that China has experienced flooding problems all summer long in many parts of the huge nation.