BEIJING - China's national observatory on Monday issued a blue alert for typhoon Merbok, which is expected to hit the southern Guangdong Province on Monday night.

At 8 am Monday, the eye of Merbok, this year's second typhoon, was above the South China Sea some 295 km to the south of Shenzhen, packing winds of up to 20 meters per second, the National Meteorological Center (NMC) said in a statement.

The NMC forecast that Merbok would move northwestward at a speed of 20 km per hour toward Guangdong and make landfall on the coast between Zhuhai and Shantou on Monday night.

But the center expected the typhoon to weaken gradually after its landfall.

From Monday to Tuesday, parts of South China Sea and the eastern coast of Guangdong will experience strong winds, while storms with up to 180 mm of precipitation are expected to affect parts of southeast Guangdong.

The NMC suggested local governments take precautions against possible geological disasters, and ships in affected areas should go back to ports.

China has a four-tier color-coded system for severe weather, with red being the most serious, followed by orange, yellow and blue.