While having weakened slightly, Hinnamnor is still a very strong typhoon. And the latest track from the Joint Typhoon Warning Center (JTWC) puts the storm on a dangerous path, with a direct landfall possible on Japan’s Yaeyama Islands, the country’s most southern and western populated territories.
The storm has become lopsided though, losing the symmetry it presented days earlier, and JTWC wrote in its forecast discussion that the eye appears to become cloud-filled, suggesting additional weakening.
Before it reaches any land areas, the storm may have weakened further. The storm is forecast to continue to slow down if not stall, causing upwelling, which is when deeper and colder water rises to the surface. Hurricanes and typhoons thrive in warmer waters, so when the water gets cooler, the tropical system lacks the fuel to maintain its strength.
As Hinnamnor nears the isolated chain of Japanese islands over the next day or two, it is expected to have winds of around 115 mph, the equivalent of a low-end Category 3 hurricane — which is still a very strong storm. Severe impacts are expected, with heavy rain, massive waves, a powerful ocean surge, and damaging winds affecting the region Friday into Saturday.
Next, the dangerous system is expected to pass northward, potentially restrengthening somewhat as it moves into open waters off the coast of China, potentially skirting the coast. Light impacts from the storm appear possible as far inland as Shanghai, but the storm appears unlikely to bring major rainfall to China, which has been facing a persistent heat wave and brutal drought.
Monday into Tuesday, the storm is forecast to pass straight through the Korea Strait, which separates mainland Japan from South Korea, with winds of up 90 miles per hour, a high-end Category 1 storm, though the storm could be even stronger, according to some forecast models.
The storm’s location by Tuesday is hardly set in stone, though, with a landfall in either mainland South Korea or Japan is possible. As of Thursday morning, the American (GFS) and European models are suggesting the storm will make a beeline right for South Korea, making landfall in the country’s southwestern tip — bringing up to 6 to 12 inches of rain.
The American Hurricane Weather Research and Forecasting (HWRF) model generally agrees with this forecast — including the extraordinary rainfall totals — but has the markedly stronger Hinnamnor make landfall further east, passing over South Korea’s highly populated Jeju Island, which lies within the Korea Straight, before making striking the mainland near Yeosu, South Korea.
Any potential outcome that brings heavy rainfall to South Korea could be devastating, as it suffered from major flooding just three weeks ago, killing at least 11 and leaving the ground moisture-laden and vulnerable to further flooding if additional intense rainfall occurs.