The weather in Hangzhou has changed from rainy days in the past.

The figure shows that the air pressure became lower at around 4 o'clock on the 8th, but it was higher before and after, which was the result of the cyclone. Due to the low air pressure in the cyclone center, rising air rotation, rainy weather, large air pressure difference between the cyclone center and the periphery, and strong wind, the weather phenomenon in Hangzhou around the 8 th is very likely to be a storm.

So choose: a.