To illustrate the roller-coaster ride of both rainfall and reservoir storage in California, see the following three graphics from the 1st day of the month for December 2014, January and February 2015.
For example, the 8-Station Index for Northern Sierra Nevada Precipitation went from 86% of normal on December 1, to 127% on January 1 and back to 86% on Feb 1st. Most other metrics statewide saw similar swings.
Jan Null, CCM
Golden Gate Weather Services