BEIJING, May 14 (Xinhua) -- Rainstorms are expected to hit China's southern regions from Tuesday to Saturday, with the country's meteorological authorities issuing their least serious blue alert.

The National Meteorological Center said on Tuesday that the middle and lower reaches of the Yangtze River, and most regions to the south of the waterway will experience heavy rainfall or rainstorms in the coming days.

Parts of Sichuan, Guizhou and Hunan provinces plus Chongqing municipality will be hit first. Then the rain will spread to more regions to the south of the Yangtze River.

Weather experts said it is the third round of large-scale rainfall in south China since April 28, saturating soil and leaving rivers there with relatively high water levels.

Experts are warning people in the affected regions to be on high alert against floods and landslides, as well as waterlogging disasters in urban areas.

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