The term flood is used when a long period of rain causes water to overflow on land, either due to poor drainage or rising water from rivers/streams/etc. Flash flooding is used when a heavy amount of rain falls very quickly in a short period of time, and causes dry areas to get replaced by large amounts of water. This results in roadways being flooded, especially under overpasses.
There are several safety rules that you can incorporate into your severe weather plan when it comes to flash flooding.
730 North Summit Street