Flooding Flooding can occur nationwide. Flash floods have become the number one weather-related killer in the United States. There was an average of 146 flood fatalities each year between the years of 1972 and 1991. This is just about equal to the number of tornado and lightning fatalities put together. Most flood deaths are due to flash floods.
Several factors contribute to flash flooding.
The two main factors are the rate of rainfall and how long the rain lasts. Some other factors are topography, soil conditions, and ground cover. Most flash flooding is caused by slow-moving thunderstorms, thunderstorms moving over the same area, or heavy rains from hurricanes and tropical storms. The important thing is to get to higher ground. The depth of the water is not always obvious.