In the strongest El Nino events, northern as well as southern Calif have received above average precipitation. In moderate El Nino events, central California may get good rains, but north of San Francisco the odds are not so good. The reason northern California is often left out of the forecast, is because it is in a transition zone between the region farther south that has the enhanced chance for above average precipitation (especially in late winter), and the region farther north (Oregon and Washington) that tend to be a bit drier than average during winter with El Nino. We're sorry, but that is what mother nature does, ON AVERAGE. In any particular case, it may or may not turn out this way, but over a large set of El Nino cases that is the tendency, based not only on empirical evidence (historical observations) but on dynamical (i.e. physical) modeling results where physical equations are used. As far as how strong the current El Nino may become by winter, it is somewhat up for grabs. At least a moderate event appears likely, but whether it will grow to become one of the very strong ones is unable to be resolved at this time. If it does become strong (with Nino3.4 and Nino3 index values of 1.5 or even 2 degrees C above average), central California will be in a better position to get a wet winter, and even farther north in California would have a decent shot at it. With the decadal climate possibly shifted from what it was between 1999 and early 2014, California also might stop having as bad a long-term drought situation. But we are not sure the decadal climate has shifted (I'm talking about the Pacific Decadal Oscillation, or PDO), since it needs to stay shifted for at least 2 or 3 years to be sure it is not just a 1 to 2 year break in the general 15-or-so year tendency. In any case, we hope California in general will get some relief from the drought, both from the El Nino and possibly from a shift of the PDO to positive phase after 1 to 2 decades in mainly negative phase. A lot going on here and it will be interesting to see the outcome!