( CNN ) -- Tropical Storm Chanthu has slowed , but it 's edging ominously closer to an area of southern China already deluged with rain and deadly floods . `` The situation is grave , '' said China 's State Council , or cabinet , according to the state-run Xinhua news agency . The council is urging local governments to step up flood control efforts . Xinhua , quoting newly released government figures , said torrential rains and floods this year already have been the worst in a decade , claiming the lives of 701 people and leaving 347 missing , . Now , Chanthu could drench some already rain-swollen areas with another 20 inches , or half meter , of rain , according to CNN Weather Anchor Jenny Harrison . Harrison said Chanthu has slowed over the last 24 hours and now is expected to make landfall Thursday evening , local time . It 's moving north-northwest at five miles an hour and is expected to come ashore between Guangdong 's coastal city of Yangjiang and Hainan 's Qionghai City . But Hong Kong , to the east , also is expected to feel the storm 's fury , as well as northern Vietnam . Chanthu already has been pounding Hainan Island , off the coast , with sustained winds of 68 miles an hour and gusts reaching 87 miles an hour . But as the storm moves inland , an area of particular concern is the region along the Yangtze River , which already has experienced the worst flooding in 30 years . Floodgates on the Three Gorges Dam have been opened to control the flow , and pictures from the scene show huge volumes of water pouring from it . Throughout the country , floods have hit 27 provinces and municipalities , affecting 110 million people , according to Xinhua . It said more than 8 million people have been relocated . About 287,000 military personnel have been mobilized in anti-flood operations , and schools are being advised to do what they can to ensure students ' safety . Xinhua also said the Qiongzhou Strait between the Chinese mainland and Hainan island was closed Wednesday as Chanthu headed toward south China . People in the affected areas are being advised to shut doors and windows and avoid outdoor activities .
NEW : Chanthu has slowed but is moving steadily closer to southern Vietnam . NEW : Tropical storm could deluge already soaked areas with 20 inches of rain . NEW : Tropical Storm Chanthu calls situation `` grave '' NEW : Chinese news agency says About 287,000 killed by floods Thursday .