Heavy rainfall swept across North and Central Jersey July 14, leading to road closures, power outages and flash flooding.

Flash flooding ranks among the top weather-related killers in the U.S. But what is it exactly, and how does it happen?

The main thing about a flash flood is its speed. By definition, the rushing waters begin within six hours after an intense storm—and often within three hours, which is why it’s called a flash.

The official definition of a flash flood warning says it is issued when “flash flooding is in progress, imminent, or highly likely.” ...

People usually only have hours of notice in advance. The disaster in Texas was a worst-case scenario.

Flash floods happen when there is heavy rainfall. There isn’t a global definition of what a flash flood is. Predicting rainfall is harder than it seems, and there are other complicated factors ...

“Flooding is a longer-term event than flash flooding: it may last days or weeks. A (flash flood is) caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours ...

Explainer - Hundreds are dead or missing in Texas flash floods. The Tasman District has been hit hard. Why is flash flooding ...