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.

As crews search for missing people after flash floods killed at least 120 in Texas, cities across the U.S. grapple with rising flood waters.

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.

Heavy rainfall caused areas of flooding on I-93 and other major roadways in Massachusetts on Thursday morning.

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.

A New Mexico mountain village is preparing for another round of monsoon rains as it tries to dig out from historic flooding that killed a man and two children.

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 .