A flash flood warning is issued when a flash flood is either imminent or already occurring. In flood-prone areas, it's crucial to move immediately to higher ground. A flash flood is a sudden and violent inundation that can develop within minutes to hours, and it can even happen in areas not currently experiencing rainfall.

Kerr County had discussed buying such things as water gauges and sirens after previous flood disasters. But as with many rural Texas counties, cost was an issue.

The National Water Center warned several rivers would face serious flooding by Friday afternoon, including the Colorado River near San Saba, Texas; the Guadalupe River near Comfort, Texas; the Guadalupe River near Kerrville, Texas; and the Guadalupe River near Hunt, Texas.

A flood warning was issued by the National Weather Service on Tuesday at 6:21 a.m. in effect until 10:30 a.m. for Delaware County.

Over the last decade, an array of local and state agencies have missed opportunities to fund a flood warning system intended to avert the type of disaster that swept away dozens of youth campers and others in Kerr County,

River gauges, sirens and clear alerts can together help emergency managers anticipate flash floods and communicate life-saving information.

A flood watch was in effect July 7 for several states, including Virginia, Maryland, Delaware, New Jersey and Pennsylvania. "Storm total rainfall of 2 to 4 inches, with local amounts up to 6 inches, is expected," the Weather Prediction Center said in a 5 a.m. ET update. "An elevated risk for flash flooding will continue."

"Flood waters have receded. The heavy rain has ended. Flooding is no longer expected to pose a threat. Please continue to heed remaining road closures," according to the National Weather Service.

A look at one Texas city’s weather warning system, as questions swirl about the timing of flash flood warnings.