TOKYO: Typhoon Hinnamnor is re-approaching Japan's southernmost prefecture of Okinawa amid unstable atmospheric conditions that are expected to lead to heavy downpours in the country's western and eastern regions, the weather agency here said on Thursday.
The Japan Meteorological Agency (JMA) upgraded typhoon Hinnamnor's classification to "violent" and warned of gale-force winds and rough seas as the powerful storm approaches the island.
It said the typhoon had an atmospheric pressure of 920 hectopascals at its centre and was packing winds of up to 270 kph as of Thursday noon, reports Xinhua news agency.
The JMA said Hinnamnor, the 11th typhoon of the season, was expected to move slowly south of Okinawa while gaining force through Friday.
From Saturday through Sunday, the typhoon will approach the Sakishima Islands and Okinawa's main island, with wind and gust speeds increasing further, with the JMA warning of wave surges a high as 10 metres in the region.
The JMA also said a weather front hitting moist air is leading to very unstable atmospheric conditions in wide regions of western and eastern Japan.
Along with thunderstorms, the meteorological agency has warned of heavy downpours and flooding in low-lying areas through Saturday.
People in the affected regions have been asked to remain vigilant for landslides, tornadoes, flooding and lightening strikes.