当突然下起暴雨时，可以用英语表达为"It suddenly started raining heavily"。
这个短语的来源是最近，你可能会听到或看到其他人用这种说法来形容突然下起大雨的情况。
下面是一些英文例句及其中文翻译，希望对您有帮助：
The sky suddenly turned dark and it started raining heavily.
天空突然变得阴暗，下起了大暴雨。
I was caught in the rain without an umbrella because it started raining heavily all of a sudden.
我没带伞，结果突然下起大暴雨，被雨淋了。
We had to cancel our picnic because it suddenly started raining heavily.
我们不得不取消野餐，因为突然下起了大暴雨。