Severe Thunderstorms, Excessive Rain and Heat Hazards

A Moderate Risk of severe thunderstorms (level 4 of 5) is in the outlook across portions of the Midwest today. Damaging winds, a few tornadoes and frequent lightning with heavy rainfall are in the forecast. Meanwhile, dangerous heat across the southern Plains into the Great Lakes, mid-Atlantic and Northeast will expand into Friday. Risk for wildfires for the central Rockies and Sacramento Valley. 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.

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