Why does it snow heavily in the south?

Since the beginning of winter, especially since 2008, the high pressure in Asia has been very active, and cold air masses have been formed continuously, which has affected China and caused large-scale gale and cooling weather. For China monsoon climate zone with great seasonal and interannual changes, this kind of weather is normal, but due to the active heating mass in the south this year, a large number of warm and humid air currents from the Pacific Ocean and the Indian Ocean frequently visit the south. When the strong cold air mass from Mongolia and Siberia quickly moves south to the south, it mixes with warm and humid air.