I was in Hong Kong once for a "Black Rain" event. One of the most intense downpours I have ever seen
They seem to have a lot more these since I came to NZ in the early 1990s. The only occasion of massive downpour I experienced was not long after the Tiananmen crackdown in 1989: a rain started at mid morning: I was still at primary school (elementary school) and schools were normally out at 12:35 pm. The rain was so bad the roads got flooded and no school bus could come. We stayed on until 2 pm as the school bus came. When I got home - it was an apartment building, the ground floor had been flooded and the water was as deep as knee level!