Why doesn't it snow in Fugu?

According to historical records, for more than 4,000 years, the climate in Fugu County has experienced many changes in temperature and warmth, but the magnitude is not large. According to the climate division of the whole country and Shaanxi Province, Fugu County belongs to the mid-temperate semi-arid continental monsoon climate. In winter, affected by Mongolian high pressure and polar cold air, the weather is cold and dry, with the lowest temperature and less precipitation. In spring, the warm air is getting stronger and stronger, the temperature is getting higher and higher, and there is more and more precipitation. In summer, it is hot and rainy due to the influence of Mongolia low pressure and Pacific subtropical ocean air mass. Warm and humid air masses and dry and cold air masses appear alternately in autumn, and continuous rain often occurs in early autumn. After 10, the temperature dropped rapidly, and the precipitation decreased obviously, resulting in crisp autumn weather. Therefore, the climate in Fugu County has the following characteristics: distinct cold, warm, dry and wet seasons, long winter and summer, short spring and autumn, rain and heat at the same time, strong solar radiation, long sunshine time, drastic temperature change, great difference between annual range and Japan, great annual variation of precipitation, and many disasters such as drought, flood, frost and hail. According to the investigation of climatic resources and landform characteristics, the county is divided into three climatic zones. The northwest of the county is a cold and dry sandstorm area with dry climate, abundant sunshine and less precipitation. The annual average temperature is 7.5 ~ 8.0℃, the average frost-free period is about 168 days, and the annual average precipitation is 380 ~ 400 mm, with less rainstorm, more hail and more sandstorms. The central part is a cold and semi-arid hilly and gully region with dry climate and sufficient heat. The annual average temperature is 8. 1 ~ 8.5℃, and the frost-free period is about 170 days, with a little more precipitation, with an annual average precipitation of 400 ~ 440 mm, and less heavy rain, heavy hail and strong wind. The southeast is a cold and semi-arid valley hilly area with dry climate and abundant sunshine. The annual average temperature is 8.5 ~ 9.0℃, and the frost-free period is 65438 0.75 days, which is the longest in the county, and the precipitation is the highest in the county, reaching 440 ~ 460 mm. There are many rainstorms, hail and strong winds in this area, and mountain torrents are easy to form along the Yellow River.