YOU SAID:

It was raining cats and dogs outside while I was eating french fries in the car park

INTO JAPANESE

駐車場でフライドポテトを食べている間に外で猫や犬を雨が降っていました

BACK INTO ENGLISH

Cats and dogs were raining outside while eating french fries in the parking lot

INTO JAPANESE

駐車場でフライドポテトを食べているときに猫と犬が外で雨が降っていた

BACK INTO ENGLISH

Cats and dogs were raining outside while eating french fries in the parking lot