National Weather Service Meteorologist Robert Baruffaldi says the storms are packed with tropical moisture.
"Every now and then, every so many years when you start to get a lot of storms back to back to back to back to back like what it looks like we’re going to be getting, that’s when you start to experience some of your flooding problems and mudslides and those sorts of things."
He recommends valley residents keep drains clear of any debris.
Forecasters say the valley will get moderate to heavy rain. And in the Sierra Nevada, several inches of snow are predicted at the higher elevations.