On the bank of the atmospheric river
October 31, 2017
During the five months between October and March over the last water year, 45 atmospheric rivers hit the West Coast. On Saturday we may see the first atmospheric river of the new water year, more than a month since it began.
Researchers at the Scripps Institution of Oceanic Research at the University of California, San Diego, have tracked the atmospheric rivers that struck the Coast through the thick of the last water year.
The very concept of an atmospheric river is relatively recent, though we've had other names for them over the years. The Pineapple Express is an example of an atmospheric river.
According to the National Weather Service, an atmospheric river is a flowing column of water vapor that moves between7.5 to 15 times the average flow at the mouth of the Mississippi River.
On average they produce 30-50 percent of the annual precipitation on the West Coast. Large ones, as we saw last winter, can bring serious flooding.
It doesn't take many atmospheric rivers to make a big difference in the water picture here. Sometimes, just a handful of big storms can make or break a ski season or a water year.
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