This slow-rising flood can take several days before the flooding begins. Most communities in the United States can experience some kind of flooding. Floods can happen anytime during the year, such as after winter snowmelts, spring thunderstorms, and fall hurricanes. Another type of flood that comes swiftly and usually with little warning is the flash flood. Flash floods are rapidly developing floods that can happen with little or no warning after an intense rainfall, a severe thunderstorm, or a dam, levee or dike breaks.
Flash floods can occur in or near mountainous areas, on small streams and even in large cities.
Water levels can suddenly rise in heavy rainstorms, leaving little time before small streams, desert-washes and drainage ditches become raging rivers. Sometimes a flash flood can unleash its deadly force in just a few minutes. If you're not certain contact the local National Weather Service office, Red Cross chapter, or Emergency Management Agency. Keep insurance policies, documents, and valuables in a safe-deposit box. Prepare a family evacuation plan.