My memory is that years ago (80s or early 90s) a small town in Southern New Jersey claimed to have recorded 25 inches in 5 hours when a Tstorm just sat over it. I have been unable to have found any mention of it when I have searched so my memory could be wrong.
Edit: Weather.com claims NJ record is 14.8 inches in 24 hours so it could be the report was wrong, never verified, or my memory is off or all three.
https://weather.com/news/climate/news/extreme-rainfall-precipitation-recorded-50-states