A flash flood is a rapid rise of water along a stream or in a low-lying urban area, the National Weather Service said. Flash flooding can result from slow-moving thunderstorms, from numerous thunderstorms that develop repeatedly over the same area, or from heavy rains associated with tropical cyclones.

Back-to-back flooding disasters in recent years — in Texas, New Mexico and Kentucky, among many others — have showed that preparing for flash flooding is a new necessity as the planet warms.

Straighter, smoother streams flow more violently than those that meander due to a reduction in friction. Areas with steeper terrain can see water accelerate downhill at a much faster rate causing a more destructive flash flood than flatter, open areas.

More than 111 people have died across six counties after flash flooding from heavy rain began affecting the state last week.

A flash flood warning is in effect until 9 a.m. for Boston and several communities south of the city, including Brockton, Quincy, and Randolph, officials said Thursday morning. The National Weather Service also issued a flood watch that will remain in effect until 4 p.m. for Rhode Island and eastern portions of Massachusetts and Connecticut.

Recent flash flooding in Texas​, New Mexico​ and North Carolina​ is highlighting the extreme danger of these natural disasters and the need to be prepared.

The mountain village of Ruidoso has returned to the grim rituals of rebuilding from flash flooding. Crews are working to clear twisted metal, broken trees and muddy debris from streets and homes days after monsoon rains triggered a deadly flash flood in southern New Mexico.

A map from AccuWeather warned that the highest-risk areas for flash flooding are Southern New Jersey, Southeastern Pennsylvania, Delaware, much of Maryland, Eastern and Central Virginia and Northern North Carolina. Downpours associated with the storms could be severe enough to cause travel disruptions and flash floods, the map said.

Flash flooding from heavy rain killed at least three people and prompted dozens of rescues in the Ruidoso area of southern New Mexico, officials said — the same area devastated by wildfires last year.

KERRVILLE, Texas — Shock has turned into grief across Texas where at least 120 people died from flash floods and more were missing as the search for victims moved methodically along endless miles of rivers and rubble Thursday.

Flash flooding has been in the spotlight in the last week, with several record breaking flood events occurring nearly back-to-back across the country. CNN’s Tyler Ory explains why they’re becoming more intense .