What is the significance of the "super historic" rainfall for July 2015 in southern California? On July 19, 2015 there was record rainfall over the Los Angeles and San Diego areas.  This is amidst a historic drought and the rain is needed.

This article:
http://www.weather.com/storms/hurricane/news/southwest-flood-threat-july-2015-tropical-storm-hurricane-dolores

states that


  Widespread showers and thunderstorms across the Desert Southwest are being fueled by moisture from former Hurricane Dolores.


and


  Los Angeles and San Diego set all-time rainfall records for the month of July on Saturday.


and


  National Weather Service meteorologist called [it] "super historic."


What is the significance of the "super historic" rainfall for July in California (July 19, 2015) in terms of climate change and water reservoirs used for municipalities?  In other words, what is the likelihood that climate change could bring more of these types of rain events in the future?  Related, what is the relative impact on water reservoirs and how much relief from the drought does such an event provide?  Does California have a long-term plan to capture more of this type of flash-flood rainfall in the future?
This event is "super historic" only because of its proximity to the coast.  It is fairly common to get flash flooding in the mountains and deserts of Socal at least a few times each summer, due to the Southwest Monsoon.  This event was different in that a dying tropical system moving north off of the coast of Mexico interacted with a trough off of the Northern California coast.  The combination of these two essentially funneled tropical moisture north directly into the coastal regions of Southern California.

Linking single events to long term global change is virtually impossible to do reliably, so I won't speculate. However one could argue that rising sea surface temperatures could allow tropical systems to stay more organized near Southern California, and increase the probability of events like this. But again, it is never a good idea to try and link a localized extreme event with a global phenomenon.

In terms of drought relief and reservoir storage these rains have virtually zero impact.  They impacted the southern third of California, while the majority of water storage is in the central and northern part of the state along the Sierras. The rain came down pretty quick and didn't soak in to any of the soils, so vegetation will still be just as dry as before the rain. California needs heavy snows in the Sierras for any serious drought relief. Although these rains have given many people a false sense of security.