1st LD Writethru: Typhoon Namtheun downgraded to tropical storm after hitting Nagasaki in Japan

Typhoon Namtheun has been downgraded to a tropical storm as it moved north over the Sea of Japan after making landfall in Nagasaki City on Japan's southwestern main island of Kyushu in the early hours of this morning, the weather agency here said Monday.

According to the Japan Meteorological Agency (JMA), the storm was downgraded to a tropical storm, also known as a depression, as of 9 a.m., but maintained advisories in western Japan for heavy rainfall and thunder and has warned of possible mudslides and rising river waters as a result of intermittent downpours.

The JMA said that the atmospheric pressure in the wake of the typhoon remained very unstable in western regions of the country and added that heavy rain could be expected through Tuesday.

Typhoon Namtheun initially hit near Nagasaki at 1 a.m. local time and subsequently made its way north at a relatively slow speed of less than 20 kilometers per hour.

The slow moving nature of the storm meant that its effects have been protracted compared to previous typhoons that have hit the nation recently, and 150 millimeters of rain are expected over the coming 24-hour period through noon Tuesday in the western area of Shikoku and in the southern-central Kansai region of Japan's main Honshu island, the agency said.

Before heading out to sea, Namtheum had a central atmospheric pressure of 1,002 hectopascals with the storm logging wind speeds peaking at 72 meters per hour near its center and through a radius of 70 kilometers.

As of 6 a.m. local time, Namtheum was located some 30 kilometers northwest of Fukuoka City, with wide swathes in the region, including Kumamoto Prefecture, which is still reeling in the wake of powerful earthquakes rocking the area in April, put under advisories for possible flooding and landslides.

Neighboring Kagoshima Prefecture, on the southern tip of Japan's Kyushu island, was also hit by the storm's powerful winds, and a man was knocked down and sustained head injuries, local media reported Monday morning.

Japan is no stranger to typhoons and the season peaks here in August and September. Of an average of 25 tropical cyclones that brew in the Pacific Ocean on average per year, around 11 chart a trajectory towards Japan with about 3 directly hitting the island.

Weather officials this year, however, have warned that complex warmer weather systems and unstable atmospheric pressure in the Pacific Ocean could lead to the formation of an inbound "super typhoon" in the days ahead.

Such a typhoon could be double the intensity of last Tuesday's Typhoon Lionrock that lashed Japan's north and northeast and saw sustained winds logging speeds in excess of 240 kilometers per hour, compared to Lionrock's 162 kph logged when it made landfall, weather officials have said. Endit