Tropical Storm Juliette is well southwest of the forecast area as of this forecast. The northern edge of the spiral arm will be sweeping across areas from the Inland Empire, Orange, San Diego, Imperial, Riverside, and San Bernardino County on your Thursday.
There are key factors with this system on me bringing rainfall totals lower than many models show. First thing is that Juliette is a low pressure system, meaning that wind would be flowing toward the system, offshore to onshore. There are times when this would come off the San Bernardino, Riverside, and San Diego County Mountains, bringing sinking air to the metros west of there. This would dry the low-levels out below 5,000 FT.
With the system not really having upper dynamics over the area, focus spots will certainly be east of San Diego for any type of moderate rain, the rest of the area will see light rain due to this dry air dynamics. It also means that even the Orange County and Inland Empire areas would only see drops, if even that, and just on big scary tropical looking sky that does not seem to do much.
You can note this by the Southern California Weather Force model showing that the San Diego Mountains have more rain than elsewhere, due to the fact they are over 4,000 FT and that the rain would evaporate less, reaching that level on this event.
Raiden Storm
Master General Meteorologist