… [A] powerful “parent” low-pressure system will deepen explosively in the Gulf of Alaska, probably undergoing bombogenesis by Wednesday as it drops toward 965 millibars. On its southern flank, the jet will tap subtropical moisture, spinning up two distinct atmospheric rivers. … For California, the edge of that storm energy may only glance the far north. A few light showers could reach the North Coast, but widespread rain looks unlikely for now. Still, forecasts this far out tend to wobble. Even a slight shift in the jet stream’s orientation could steer one of those atmospheric rivers closer to California. 

Other atmospheric river news:

• Newsweek: Strong atmospheric river takes aim at California
• Nature: Communications Earth & Environment: Atmospheric rivers emerge as future freshwater reserves and heat stocks