CHANGSHA, Jan. 20 (Xinhua) -- Schools have been suspended and emergency workers are on standby as Chinese provinces brace for a week-long cold wave.

China's National Meteorological Center (NMC) announced a blue alert Wednesday morning for snow storms that will sweep southern China in the coming days.

Temperatures could drop by 14 degrees Celsius, with cities such as Shanghai and Changsha to see record low temperatures.

Cold air moving south will bring heavy snow to regions along the Yangtze River from Wednesday to Saturday, with a forecast of up to 30 millimeters of snow in some areas, the NMC said.

Schools in Changsha have been told to start winter holiday three days earlier than previous years, while education authorities in Hangzhou have allowed students not to come to school.

Internet users have called the cold front a "bossy cold wave" for its strength and reach.

Local Chinese agricultural authorities have warned farmers to add organic fertilizers to keep crops and vegetables from being damaged by the cold and to reinforce their plastic greenhouses to reduce damage.

Nonetheless, farmers say loss is inevitable. "The temperature will stay minus zero for several days. Only ten percent of the vegetables will survive," said Zhu Dazhi, a farmer in central China's Hunan province.

In affected provinces, electricity companies have made emergency plans to remove ice on key facilities. x Experts say the possibility of harsh conditions similar to the winter storms in 2008 is small, as the cold period will be shorter.

In China's four-tier color-coded weather warning system, red represents the most severe weather, followed by orange, yellow and blue.