Only early this morning did the two main weather models for Southern California finally come into agreement. Last night, the NAM was still forecasting a big Tuesday storm and the GFS was predicting minor rain chances through Friday. They finally split the difference and now foresee a big storm on Wednesday (though not as big as the NAM was anticipating) tapering off on Thursday.
Or at least, that's what the weather folks are saying at the moment. This is a cut-off low (i.e., "weatherman's woe") so any forecast has to be qualified with the reminder that these things are hard to gauge and that plans can change rapidly. Keep the umbrella handy.