Today I saw a surprising video image of guerrilla rain on TV. In the video, only in some-hundred-meters square area, torrential rain was pouring heavily for a short period.
One taxi driver said in the interview, "When I was driving in the sun, all of a sudden, a heavy rain attacked my car, then after three minutes I got through. I felt surprised and scared."
It is an unpredicted pinpoint attack like guerrilla. Not gorilla.