This evening from Dave Hovde of SLO: “Update on short-term forecast: The Friday into Saturday system looks to arrive Friday morning, peak in the afternoon but linger a bit into Saturday morning.  I had said less than .25" but looks like up to .50" is possible based on recent modeling.”

From NOAA Forecast discussion: 
Today will be the last of the mild and dry days before a significant shift towards a progressive (and wet) weather pattern takes hold over at least the next 7 to 10 days across the Bay Area and Central Coast. At least 3 to 4 wet systems will move over or near the region through this time frame-- with the system arriving midweek next week looking to be the most significant. One weather forecaster described it as a “conga line of storms,” a term that has become more prevalent in the last decade or two.