Flash floods are the number one weather-related killer in the United States. Six inches of fast moving water can knock you off your feet. Twenty-four inches of water will carry away most automobiles. Nearly half of all flash flood fatalities are auto related. Be aware that roadways may not be intact under floodwaters. Flash flooding occurs within 6 hours of the rain event. Flash flood waters can move at incredible speeds, uprooting trees, moving boulders, and destroying bridges and buildings. Most flash flooding is caused by slow-moving thunderstorms, thunderstorms repeatedly moving over the same area or heavy rains from hurricanes and tropical storms. Occasionally, floating debris or ice can restrict the flow of water at natural or man-made obstructions. Flash flooding can occur downstream when the ice or debris is suddenly released.

Environmental Clues:

• Listen for distant thunderstorms – runoff from a faraway thunderstorm could be headed your way.
  
• Look out for rapidly rising water.
  
• When driving look out for flooding at highway dips, bridges and low areas.

Warnings:

• Flash Flood Watch or Flood Watch – Flash flooding or flooding is possible within the designated watch areas – Be Alert.
• Flash Flood Warning or Flood Warnings – Flash flooding or flooding has been reported or is imminent - take necessary precautions at once.
• Urban and Small Stream Advisory - Flooding of small streams, streets and low-lying areas, such as railroad underpasses and urban storm drains, is occurring.