A flash flood is a type of flood event that occurs quickly, usually within 6 hours of a rain event. Flash floods can also result from dam breaks or even an ice jam on a river or stream during the winter months. More often than not, they are usually isolated events, affecting only one or a few small streams in a particular area and often do not receive the widespread notoriety of larger weather events. When a flash flood occurs, the water in the affected small stream or waterways rises very rapidly inundating the surrounding area. Within minutes, what was once a harmless looking stream can become a raging rapid capable of rolling boulders, tearing out trees, and destroying buildings and bridges.
Time is of the essence.
Flash floods can occur just about anytime of year in the region. Prolonged cold spells during the winter can cause a build up of river ice. Once this ice breaks apart and moves downstream, it can become jammed against a bridge resulting in flash flooding up stream of the jam. During the spring and summer months, slow moving thunderstorms are usually the catalyst. These thunderstorms are capable of producing several inches of rain in just one hour, resulting in flash flooding.