Read the isobar map of East Asia at a certain time (unit: hectopascals) and complete the question 17 ~ 19. The name of the weather system and the weather it may affect.

A. Sandstorm is weather formed by cold front. According to the analysis of air pressure data in the figure, P is the high pressure center in the figure, and the air flow sinks and the weather is sunny, which does not meet the meaning of the question;

B. According to the analysis of air pressure data in the figure, P in the figure is the high pressure center, which does not meet the meaning of the question;

C. According to the analysis of air pressure data in the figure, P in the figure is the center of high pressure, the air flow sinks and the weather is fine. P in the picture is in the North Pacific, so it affects the subtropical high in China. At this time, the middle and lower reaches of the Yangtze River in China entered the summer drought weather, so it is correct;

D. according to the analysis of the air pressure data in the picture, P in the picture is the high pressure center, which does not meet the meaning of the question.

So choose: C.