8
$\begingroup$

Whenever weather warnings come up, I have heard of both a flood watch/warning and a flash flood watch/warning.

What is the difference between a "flood" and a "flash flood"? Are there any specific meteorological/weather forecasting patterns that distinguish one from the other?

$\endgroup$
6
$\begingroup$

Flood: An overflow of water onto normally dry land. The inundation of a normally dry area caused by rising water in an existing waterway, such as a river, stream, or drainage ditch. Ponding of water at or near the point where the rain fell. Flooding is a longer term event than flash flooding: it may last days or weeks.

Flash flood: A flood caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours. Flash floods are usually characterized by raging torrents after heavy rains that rip through river beds, urban streets, or mountain canyons sweeping everything before them. They can occur within minutes or a few hours of excessive rainfall. They can also occur even if no rain has fallen, for instance after a levee or dam has failed, or after a sudden release of water by a debris or ice jam.

Source: National Weather Service Weather Forecast Office

$\endgroup$
  • $\begingroup$ In summary, a flood is a long-term event that covers normally dry areas whereas a flash flood is a short-term event that covers low-lying areas. $\endgroup$ – user402 May 6 '14 at 17:53
  • $\begingroup$ @edmastermind29: Main thing is that flash floods, do not last more than a few hours - unless they turn into a flood; though my experience is this normally only happens in man made drain systems, since they allow for the conference of water in much more affective ways than are naturally possible. $\endgroup$ – blunders May 6 '14 at 18:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy