BEIJING, May 14  -- The National Meteorological Center (NMC) on Thursday issued a blue alert for torrential rain, thunderstorms and hail that will sweep parts of south China.

Heavy rain will hit the provinces of Hunan, Jiangxi, Zhejiang, Guizhou as well as Guangxi Zhuang Autonomous Region from Thursday to Friday. Thunderstorms and hail are also expected in some parts, the NMC said.

The weather observatory advised residents to stay indoors and on alert. It also asked local authorities to brace for the severe weather.

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