For the past two weeks, northern California has been getting pounded by storms for the past two weeks, and the entire region is now under daily flood warnings.

But according to meteorologists, not only is this perfectly normal, it's welcome news for a state living through its worst dry spell of the past 1,200 years.

"The heavy rains will put a noticeable dent in the state's three-year drought," meteorologist Jeff Masters wrote on his blog.

The new storms are being caused by at "atmospheric river," which is a narrow but voluminous trail of water vapor that has broken away from a larger band of weather concentrated around the equator.

Here's one view of the system, from radars run by the University of Wisconsin.


And another, from the National Weather Service.

According to the National Oceanic and Atmospheric Administration, about 30 to 50 percent of annual precipitation in west coast states occurs in just a few atmospheric river events, meaning they make significant contributions to the states' water supplies.


But for the moment, it's wreaking havoc, knocking power out and causing hundreds of flights to be cancelled. Resident have taken to calling it #hellastorm on social media.


Residents are bracing for more.


But minders at Yosemite National Park are thankful for the rain. "To see Yosemite Falls coming to life this morning is truly exhilarating," said Don Neubacher, Yosemite National Park Superintendent.

Here's a before-and-after-the-storm view of the park's Yosemite Falls:


Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.