The Hong Kong Observatory reported that the weather system has become a severe tropical storm. Tropical Storm Chanthu is now about 267 miles (430 kilometers) south of Hong Kong and is forecast to move northwest at about 7 mph (12 kph) and edge closer to the coast of Guangdong. The observatory said the storm has moved on a more westerly track over the past few hours. It said winds will gradually strengthen.

Late Tuesday, the Joint Typhoon Warning Center said the storm has sustained winds of 63 mph, and they're expected to grow to nearly 75 mph. The center is operated by the U.S. Navy and Air Force in Pearl Harbor, Hawaii.

The storm is expected come ashore late Wednesday or early Thursday, local time.

This latest storm comes on the heels of major flooding and landslides in central China. The death toll has risen to 41 as a result in two provinces, the state-run Xinhua news agency reported Tuesday. The floods caused 26 deaths in Sichuan province and left another 30 people missing, the news agency reported, citing the Sichuan Provincial Water Resources Department. The state-run news agency also reported that at least 15 people are dead and 54 are missing in northwest China's Shaanxi province.

Of particular concern is the massive Three Gorges Dam in Hubei province. With the Yangtze River already running at record levels, engineers have opened up the flood gates. The Yangtze is fed by three major tributaries, and it flows east, from Sichuan, toward the dam. Water flows near the dam are comparable to record flows during devastating floods in China in 1998.

The Three Gorges, the world's largest dam, was completed last year. So far, it is holding up.

Xinhua quoted Yuan Jie, director of the dam's cascade dispatching center, as saying that, "Compared to 1998, the biggest difference is the Three Gorges Dam. Without it, thousands of soldiers and rescuers would have been needed to fight the floods."

Elsewhere, more than 230,000 people have been evacuated from the city of Guangan in Sichuan, after the worst flooding there in 160 years. There's no power, no clean water, and the only way around is by boat.

The wild weather also has cut off roads, flattened homes, destroyed power facilities and flooded farmland in Ankang City, the worst-hit area, Xinhua reported. Flood control authorities say the lives of nearly 1.5 million people have been disrupted by flooding in 23 counties and cities in the southern regions of the province.

Other areas that have been inundated include the city of Chongquing, and Anhui and Hunan provinces, according to Xinhua. Altogether, more than 9 million people have been affected by floods and landslides, it said.

According to the observatory website, the outer rain bands of Chanthu will affect Hong Kong overnight and local winds will gradually increase. The government weather website said that since there will be swells, people are advised to stay away from the shoreline and not engage in water sports. All small vessels, including low-power vessels and fishing vessels in open seas, should seek shelter as soon as possible, the government said.