Rivers in the sky: Why California is flooding

It's hard to believe that after five years of record drought, many Californians are hoping that this winter's weekly deluges will come to a swift conclusion. The latest storm, which struck over the weekend and ended on Tuesday, has forced thousands to evacuate, including urban residents in San Jose, as floodwaters continue to rise and levees are strained. This winter demonstrates how too much of a good thing -- in this case, rain and mountain snow -- can lead to severe problems. SEE ALSO: Insane drone footage shows massive damage and flooding at California's Oroville Dam This is increasingly important, since human-caused global warming is already causing both ends of the weather extremes spectrum -- too little water and too much -- to occur more frequently and with greater intensity. So, what is it about these California storms that separates them from ordinary low pressure systems that affect other parts of the country?