National Weather Service United States Department of Commerce

Severe Weather Across the Center of the Nation; Fire Weather Concerns for Southwest and California; Snow for the Central Rockies

Severe thunderstorms will continue to impact the center of the Nation through today. Very large hail, strong tornadoes, and damaging winds are expected from the Great Lakes into the central/southern Plains; Flash flooding is possible for portions into the mid-Mississippi Valley. Critical fire weather conditions for the Southwest and central valley of California today. Winter hangs on for Rockies. Read More >

 

Definitions of Flood and Flash Flood


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.