At long last, a series of Pacific storm systems is producing sorely needed rain and mountain snowfall in California, which has been suffering from one of its worst droughts in at least 500 years. The storms, which began*Thursday and are forecast to last through the weekend, are likely to have their greatest impact in Central and Northern California, including the agricultural powerhouse region that is the San Joaquin Valley.
Parts of Central California may receive as much as 4 inches of rain through the weekend, according to the National Weather Service, while 2 feet or more of snow may fall*in the California Cascades and parts of the Sierra Nevada Mountains.
Victor Murphy, a National Weather Service meteorologist in Dallas, said he expected the northern half of California to see 2-4 inches of rain over the next week with as much as 4-8 inches in some locations.*“It certainly would appear as though this storm can indeed provide some drought relief,” he said.
The storms are tapping into a phenomenon known as an “atmospheric river,” which is a relatively narrow stream of moisture-rich air extending from the tropics northeastward across the Pacific. Atmospheric rivers have helped end California droughts before, according to research by Michael Dettinger of the U.S. Geological Survey and the Scripps Institution of Oceanography. Dettinger’s research, which was published in the December issue of the Journal of Hydrometeorology, found that atmospheric river events can effectively end even major droughts in California within just one month. In fact, Dettinger found that most droughts in the West end abruptly, with one very wet month pulling the state from a significant precipitation deficit to a surplus.