Another atmospheric river hits California with heavy rain and threat of major flooding

A new storm system hit Northern California on Friday with heavy rain, threatening millions with dangerous flood conditions as snow from previous storms melts. Flood advisories or warnings were issued by the National Weather Service for areas around the San Francisco Bay, the central coast and the Sacramento and San Joaquin valleys. Southern California saw generally lighter rain.

The atmospheric river, known as a "Pineapple Express" because it brought warm subtropical moisture across the Pacific from near Hawaii, was melting lower parts of the huge snowpack built in California's mountains by nine atmospheric rivers early in the winter and later storms fueled by a blast of arctic air.

The snowpack at high elevations is so massive it was expected to be able to absorb the rain, but snowmelt was expected at elevations below 4,000 feet, forecasters said.