This afternoon (Tuesday, Jan 19th) Southern California experienced a fast-moving thunderstorm that resulted in very strong rotating winds and a tornado or perhaps several tornadoes.
The storm flipped cars and submerged streets. 
Here is a radar image from this afternoon. You can see a loop of the storm moving over California here: http://www.weather.gov/sat_loop.php?image=wv&hours=24
More information:
http://www.cbsnews.com/stories/2010/01/19/national/main6117105.shtml