ATMOSPHERIC RIVERS ARE California’s drought-busters. As we saw in the recent series of storms between January 7 and 10, a single wet weekend can dramatically reverse the state’s water accounts.

The state still hasn’t completely pulled out of the drought. But just a few days after those storms, the California Department of Water Resources increased its water delivery forecast for 2017 from 45 percent to 60 percent for water agencies that rely on the State Water Project.

Atmospheric rivers are just what they sound like: a column of water carried aloft by a narrow band of wind. The moisture usually originates in the tropics of the eastern Pacific Ocean and travels all the way across the sea in a narrow band before striking the U.S. coast – usually somewhere in California.

These events can deliver as much as 50 percent of California’s water supply in as few as eight storms every year. But until recently, predicting them has been difficult. Meteorologists had no way to tell where an atmospheric river would strike, how wet it would be, or for how long. Now they have a variety of tools that help provide those answers.

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