Why is the weather abnormal now? It's mid-April in Yuxian, and it's still snowing? The south has not touched a drop of water?

La Nina phenomenon. Under the influence of La Nina phenomenon, the water temperature in the equatorial western Pacific Ocean is high, and the water evaporation is increased, resulting in abnormal meridional circulation in East Asia. In addition, since the beginning of spring, the northerly airflow has prevailed in northern China, while the warm and humid airflow in the southeast is relatively weak. As a result, cold waves and strong winds frequently appear in the north. And we know that at this time, East Asia is being affected by the Asian high. Therefore, it has strengthened the power of cold air from Siberia to move south rapidly. After the cold air crossed the border, the temperature plummeted. One condition is that there must be cold air, which comes from the polar regions and from the alpine regions. The cold air affecting our country in the early winter this year is relatively weak, and the frequency is not much. Even with the cooperation of warm and humid airflow, it is not easy to snow without cold air. Therefore, before January, there was relatively little precipitation, dry air and high temperature in most parts of our country. However, in January, great changes have taken place in the atmospheric circulation, which makes the cold air activity in our country more active. After the cold air is active, the warm and humid airflow at low latitudes is gradually strengthened, which just happens to combine the cold and the warm. Therefore, during this period of time, the cold air is relatively strong, the cold air activity is relatively frequent, and the warm and humid air flow is relatively strong. These two air flows have the same influence and meet coincidentally. Therefore, recently, especially in the Yangtze River basin, there have been more rainy and snowy weather, and the low temperature weather has been maintained for a long time.