Want a good view of the storms hitting California and willing to work a bit for it? Download and install WeatherScope. This is a free application for looking at the huge quantities of free weather data out there. The user interface isn't great but the functionality is.
The most frequent updates on the atmosphere (about every 5 minutes) come from weather radar. WeatherScope has access to the past 24 hours of raw US radar data, while the free weather websites will show you about 45 minutes worth. 24 hours is enough to see a lot of patterns - arcs of rain sweeping in from the Pacific, blossoming into downpours when they hit a ridge.
Here's a WeatherScope saved view for base reflectivity from three overlaid radars covering north-central California (San Francisco, Sacramento, Beale AFB): sf-radars.wxscript
At least on the Mac, WeatherScope should automatically open
.wxscript files. After opening the file, you should see a map of California. In the WeatherScope menu bar, go to "Window : Show Animator" and click the Play button in the Animator window. It will take a while for WeatherScope to download 24 hours worth of animation, so you won't see much to start with. Once it fills in hopefully you'll feel it was worth waiting for. Leave WeatherScope running and it will download new images as they become available.