A gusty, rain-soaked storm swept through the Pacific Northwest and Northern California this week, killing at least two people and knocking out power for hundreds of thousands of customers. The dangerous weather,

"The average atmospheric river carries an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi," NOAA states.

Heavy downpours fell over much of Northern California on Friday, causing small landslides, overflowing a river and flooding some streets, including in parts of San Francisco. Meanwhile tens of thousands of people were still without power in the Seattle area after several days in the dark.