New atmospheric river storm barrels toward California

California braced Thursday for the arrival of another atmospheric river that forecasters warned will bring heavy rain, strong winds, thunderstorms and the threat of flooding to a state still digging out from earlier storms.

California braced Thursday for the arrival of another atmospheric river that forecasters warned will bring heavy rain, strong winds, thunderstorms and the threat of flooding to a state still digging out from earlier storms.

The flood threat will come from the combination of rain and melting of 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 new atmospheric river is a type known as a "Pineapple Express" because it is a deep tap of warm subtropical moisture stretching over the Pacific to Hawaii. Its greatest impacts were expected in northern and central California.

The snowpack at high elevations is so massive it should be able absorb the rain, forecasters said. But elevations below 4,000 feet (1,219 meters) will see melting and runoff. The National Weather Service characterized the flood threat as "moderate."

At high elevations the storm was predicted to dump heavy snow, as much as 8 feet (2.4 meters) in some locations.

California's Sierra Nevada snowpack, which provides about a third of the state's water supply, is more than 180% of the average on April 1, when it is historically at its peak.

So much snow has fallen in the Sierra and other mountain ranges that residents are still struggling to dig out days after earlier storms.