TOKYO, Sept 17 (Reuters) – The Japan Meteorological Agency issued a special typhoon warning on Saturday for Kagoshima Prefecture in Kyushu, the southernmost of Japan’s main islands, as the region braces for a powerful and potentially devastating super typhoon. The warning came after the weather service earlier in the day urged residents to evacuate parts of Kyushu, ahead of Typhoon Nanmadol, which is expected to bring up to half a meter (20 inches) of rain when it makes landfall on Sunday. Classified as a super typhoon by the US Navy’s Joint Typhoon Warning Center, Nanmadol has the potential to be the most destructive tropical storm to hit Japan in decades. Sign up now for FREE unlimited access to Reuters.comSign up The 14th typhoon of the season was near Japan’s southern Minami-Daito Island and was moving northwest at 20 km/h (12 mph) on Saturday afternoon. Winds at the center of the storm were gusting to 198 km/h (123 mph) and gusting to 270 km/h (167 mph), the JMA said. “Unprecedented” storms and rainfall could hit the area, JMA official Ryuta Kurora told a televised news conference, urging residents there to evacuate before nightfall. Southern Kyushu could receive 500 mm (20 inches) of rain on Sunday, while the central Tokai region could see 300 mm (12 inches) according to the agency’s forecast. The special typhoon warning will be the first such alert for any prefecture north of the Okinawa island chain, domestic media reported. Kyushu Railway Co ( 9142.T ) began cutting some train lines on Saturday ahead of wider suspensions on Sunday. Hundreds of weekend flights in the southern region were cancelled, broadcaster NHK reported, causing confusion for passengers traveling over the weekend. Store chain Seven-Eleven Japan will temporarily close about 610 stores in the Kyushu and Chugoku regions starting Saturday night, local media reported. The storm was forecast to curve east and pass over Tokyo on Tuesday, before moving out to sea on Wednesday. Domestic broadcasters broadcast footage of strong winds and rain already lashing Japan’s southern island chain of Okinawa as the storm approached. Sign up now for FREE unlimited access to Reuters.comSign up Reported by Rocky Swift in Tokyo. Editing by William Mallard, Lincoln Feast and Alex Richardson Our Standards: The Thomson Reuters Trust Principles.