Atmospheric river storm hits Northern California, bringing rain and snow

A storm system known as an “atmospheric river” hit Northern California and Oregon on Tuesday, bringing days of heavy rains and snow to the area. 

The atmospheric river is a “deep and fast-moving” channel of wind in the atmosphere that transports water vapor from the tropics. Throughout the whole week, the storm system is expected to cause unprecedented rainfall, flash flooding, and mudslides. 

According to William Churchill, a meteorologist with the National Weather Service’s Weather Prediction Center, parts of the northwest can see a rate of rainfall of up to an inch per hour. 

“California in general can largely use this precipitation,” Churchill said. “Unfortunately, when too much occurs all at once, it does cause problems.”

While it is not uncommon to see these atmospheric storms hit the West, this one is unusual because of its strength and duration, Churchill added. 

As of Tuesday evening, at least two to six inches of rain had fallen in the most affected areas as the storm moved through the Rocky Mountains and the Sierra Nevada. 

Almost five million people in Seattle and Portland were placed under high wind warnings on Tuesday after wind gusts reached up to 60 miles per hour. In Portland, the heavy winds caused power outages, leaving more than 135,000 customers without power. 

The National Weather Service issued a flood advisory for the Bay Area on Tuesday after the region was hit with heavy rains that caused flooding on major highways. 

The storm is expected to bring more rain to Central and Southern California throughout Wednesday when the storm is expected to regain momentum.