Science behind atmospheric rivers

Published: Mar. 22, 2023 at 2:19 PM CDT
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QUAD CITIES, Iowa/Ill. (KWQC) - Rounds of heavy rain, heavy snow and devastating flooding have dominated the weather headlines over the last several weeks.

The culprit? Atmospheric rivers.

It’s a term that has become recently popularized, but it’s not a new meteorological phenomenon.

Atmospheric rivers are similar to actual rivers, but in the sky.

An atmospheric river is a large, narrow, continuous band of moisture that carries water vapor from the tropics to higher latitudes.

The 200 to 400 miles wide atmospheric river moves inland, and the mountains force the moisture upward.

As the moisture cools and condenses and forms clouds, rain and snow form and at times, atmospheric rivers can produce heavy durations of rain and snow, leading to potential flooding and mudslides, similar to what California has experienced during the winter season.

Atmospheric rivers aren’t always a bad thing. They can bring relief to drought-stricken areas.

In fact, parts of California receive nearly half of the year’s precipitation from atmospheric rivers.

A common atmospheric river is the “Pineapple Express,” which happens when moisture builds in the tropics near Hawaii and moves into the west coast of the United States and Canada.