Flash floods are the #1 weather-related killer in the U.S. since they can roll boulders, tear out trees, and destroy buildings and bridges. A flash flood is a rapid flooding of low-lying areas in less than six hours, which is caused by intense rainfall from a thunderstorm or several thunderstorms. Flash floods can also occur from the collapse of a man-made structure or ice dam.
What is a Flash Flood?
A flood caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours. Flash floods are usually characterized by raging torrents after heavy rains that rip through river beds, urban streets, or mountain canyons sweeping everything before them. They can occur within minutes or a few hours of excessive rainfall. Flash floods can reach their peak volume in a matter of a few minutes and often carry large loads of mud and rock fragments. They can also occur even if no rain has fallen, for instance after a levee or dam has failed, or after a sudden release of water by a debris.
Flash Flood Watches and Warnings
Flash Flood Watch - Flash flooding is possible. Be prepared to move to higher ground; listen to NOAA Weather Radio, commercial radio or television for information.
Flash Flood Warning - A flash flood is occurring; seek higher ground on foot immediately.
Driving Flood Facts
The following are important points to remember when driving in flood conditions:
•Six inches of water will reach the bottom of most passenger cars causing loss of control and possible stalling.
•A foot of water will float many vehicles
•Two feet of rushing water can carry away most vehicles including sport utility vehicles (SUV’s) and pick-ups.
•Do not attempt to drive through a flooded road. The depth of water is not always obvious. The road bed may be washed out under the water, and you could be stranded or trapped.
•Do not drive around a barricade. Barricades are there for your protection. Turn around and go the other way.
•Do not try to take short cuts. They may be blocked. Stick to designated evacuation routes.
•Be especially cautious driving at night when it is harder to recognize flood dangers.