Strong Atmospheric River Bringing Heavy Rain to the Pacific Northwest; Areas of Snow in the North-Central and Eastern U.S.

A strong atmospheric river will bring prolonged heavy rainfall along with gusty winds to the Pacific Northwest through much of this week. The heavy rainfall may lead to widespread urban and river flooding. Accumulating snow is expected over parts of the central Appalachians and Mid-Atlantic today as well as the Upper Midwest and the Upper Great Lakes this evening into Tuesday. 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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