With Severe Weather Awareness Week beginning today, each day we will be focusing on different topics. Today, our main focus is flash flooding.
Each year, more deaths occur due to flooding than from any other thunderstorm related hazard, resulting in more than 140 fatalities each year. Most flash floods are caused by slow moving thunderstorms, thunderstorms that redevelop over the same area, or heavy rains from tropical storms and hurricanes. These floods can develop within minutes or hours depending on the intensity and duration of the rain, the topography, soil conditions, and ground cover.
A flash flood is a rapid rise of water along a stream or low-lying urban area. Flash floods can roll boulders, tear out trees, destroy buildings and bridges, and scour out new channels. Rapidly rising water can reach heights of 30 feet or more. Flash flood-producing rains also can trigger catastrophic mud slides.
Almost half of all flash flood fatalities occur in vehicles. Many people do not realize two feet of water on a bridge or highway can float most vehicles. If the water is moving rapidly, the car, truck, or SUV can be swept off the bridge and into the creek or downstream with the flowing water. Water can erode the road bed, creating unsafe driving conditions. Underpasses can fill rapidly with water, while the adjacent roadway remains clear. Driving into a flooded underpass can quickly put you in five to six feet of water. Many flash floods occur at night when flooded roads are difficult to see. When you approach a flooded road, TURN AROUND, DON’T DROWN!
Article Courtesy NWS Des Moines