Multiple parts of Central Texas, including Kerr County, were shocked by flash floods Friday when the Guadalupe River and others rose rapidly.

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. And there’s no more dangerous time for a flash flood than after dark;

An analysis of National Weather Service job vacancies found that in more than a third of offices overseeing flash flood hotspots, one or more of three senior leadership roles are open.

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.

Portions of west-central Chicago experienced localized flash flooding on July 8. Find out how to stay safe in flooded areas.