Similar to scales gauging hurricane, wind, or tornado intensity, could aid flood response and water management, especially in the West.
A team of researchers led by Scripps Institution of Oceanography at the University of California San Diego has created a scale to characterize the strength and impacts of “atmospheric rivers,” long narrow bands of atmospheric water vapor pushed along by strong winds. They are prevalent over the Pacific Ocean and can deliver to the Western United States much of its precipitation during just a few individual winter storms.
Atmospheric rivers (ARs) are the source of most of the West Coast’s heaviest rains and floods, and are a main contributor to water supply. For example, roughly, 80 percent of levee breaches in California’s Central Valley are associated with landfalling atmospheric rivers.
The scale, described today in the February 2019 Bulletin of the American Meteorological Society, assigns five categories to atmospheric rivers using as criteria the amount of water vapor they carry and their duration in a given location. The intention of the scale is to describe a range of scenarios that can prove beneficial or hazardous based on the strength of atmospheric rivers.
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Image via University of California San Diego
