The National Flood Insurance Program (NFIP) defines a flash flood as a severe storm that drops much rainfall in a short time. Flash floods can occur in all fifty states, areas with steep slopes and narrow stream valleys are particularly vulnerable. In hilly areas, the high-velocity of water flow and short warning time makes the flash floods hazards and very destructive. There have been more deaths in the United States caused by flash floods than any other type of flooding. For more information about the NFIP and floods go to Flood Insurance