It is a big travel weekend for some and statewide we have some items to mention: Tule Fog in the Central Valley will be an issue into early Thursday. Across Southern California there is a Santa Ana wind event which also winds down a bit Thursday morning.
An upper level system is approaching from the SW. Light southerly wind flow and mild temps and partly cloudy skies will likely be all we get from the system. It is trying to bring moisture in but it is doing so at mid and upper levels and the lower levels are likely too dry to get anything from the system. Perhaps some sprinkles best chance will be at higher elevations. Winds will be onshore so some marine clouds at the coast with mist or drizzle in the night and mornings is possible.
A weak cold front will wash out over the Central Coast Friday night into Saturday morning with scattered drizzle or a light shower. I doubt anyone gets much from this. Higher elevations of the coastal hills might see up to .10" but I think most locations get hundredths, if anything.
Now we can tackle the larger system Sunday night into Monday. All models agree it is coming, I think the only question is rain potential. I have seen forecasts advertising more than an inch, I think it'll be less than that (as of this writing).
The system is vigorous with an over-water trough digging our direction over the weekend. The issue with the system I think is that it doesn't look to pull up a lot of sub-tropical supply before arrival. I still think .20-.75" with some local totals higher than that, like in wind facing coastal hills. The bulk of the rain comes Sunday night into early Monday with lingering showers and a wind Monday afternoon. 15-30+mph winds from the NW will make Monday a blustery day with partly cloudy skies developing by Monday afternoon and night.