LHASA, Feb. 7 (Xinhua) -- Southwest China's Tibet Autonomous Region upgraded its snowstorm alert on Thursday afternoon, forecasting heavy snow in some southern counties of the region.

In the 24 hours starting from 4 p.m. Thursday, heavy snow will hit counties of Nyalam and Jilung in Xigaze City, and Burang County in Ali Prefecture, said the regional meteorological observatory.

The observatory upgraded the snowstorm alert from yellow to orange, based on a four-tier color-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.

It said the new snowfall will increase the depth of snow drifts already in these areas, reminding drivers of anti-skidding measures and herders of disaster prevention.

The Tibetan New Year and the Spring Festival, or the Lunar New Year, coincided and fell Tuesday this year. The Tibetan New Year is normally celebrated by religious rituals, prayers, horse races, family gatherings and feasts.