鉄てっ砲ぽう雨あめ

noun

pelting rain; torrential rain; downpour

Vivid, somewhat colloquial term for rain that falls so hard it feels like bullets. Often used in spoken Japanese or informal writing.

• 急きゅうに鉄てっ砲ぽう雨あめが降ふってきて、ずぶ濡ぬれになった。

  Suddenly a pelting rain started and I got soaked.

• 鉄てっ砲ぽう雨あめの中なかを歩あるくのは危あぶないよ。

  It's dangerous to walk in such a torrential rain.