This winter, parts of drought-stricken California have been besieged by heavy flooding, mudslides, and feet of snow. The cause? A meteorological phenomenon known as an atmospheric river, which carries high concentrations of water vapor in narrow bands from the warm tropics up to western North America.

 

In the western U.S., atmospheric rivers are relatively common and are critical providers of winter rain and snow. However, they can also be a source of extreme flooding and costly damage to transportation networks, public utilities, and other infrastructure. While the economic and social impacts of strong atmospheric rivers are well understood, we know much less about how they can impact ecosystems.