San Francisco could see as much as six inches of rain over the next week as a moisture-packed storm known as an atmospheric river works its way south from the Pacific Northwest.

A warm, wet storm originating in Hawaii will be pulled north toward California bringing heavy rain and localized flood risk.

A strong Pacific storm will begin to uncoil across Oregon, Washington and Northern California through the weekend, promising heavy rain and snow that will replenish water supplies but could also unleash destruction.