Analysis of the May 2019 Atmospheric Circulation and Weather
The main characteristics of the general atmospheric circulation in May 2019 are as follows. There were two polar vortex centers in the Northern Hemisphere. The polar vortex in the north of Canada was stronger than usual and was closed to normal in the south of Novaya Zemlya. The 500 hPa geopotential height presented the distribution of a fourwave pattern in the high latitude of Northern Hemisphere. The strength of Western Pacific subtropical high was similar to normal years, and the south branch though was a little weaker. The monthly mean temperature across China was 16.2℃, closed to normal. The temperature fluctuated greatly in this month, and Yunnan Province experienced the warmest mean temperature since 1961. The monthly mean precipitation amount over China was 69.5 mm, same as the normal amount (69.5 mm). In addition, seven regional torrential rain processes occurred in China this month, and the extremely severe weather like hail and thunderstorms hit Beijing. Severe droughts were found in Jianghuai, Huanghuai and Yunnan, and four sanddust events happened in the northern part of China.