Jeff Masters Meteorologist - Atmospheric rivers

I welcome back to DITD Jeff Masters of the Yale Climate Connection. Jeff, worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. He has a Ph.D. in air pollution meteorology from the University of Michigan. In 1995, he co-founded the Weather Underground weather channel. On Monday Jan 22nd , a relatively weak atmospheric river, along with favorable winds in the mid-to-upper atmosphere, combined to deliver a deluge to San Diego, with the city seeing 2.73 inches of rainfall in a very short amount of time causing major flooding and destruction of property. Now California is being slammed up and down the coast in the same manner. What's going on?