Meteorological Events That Led to the 2017 Oroville Emergency Spillway Use (Invited Presentation)

The winter of 2016-2017 in northern California featured a series of intense atmospheric rivers that affected the Feather River drainage basin. Oroville Dam, which is located in the Upper Feather River basin, received a watershed-average of approximately 26.5 inches of precipitation above climatological normals from December 2016 through February 2017 based upon PRISM data. Even though none of the storms during this three month period were estimated to have a return period greater than 100 years, the combined effect resulted in dangerous inflows into Lake Oroville. In response to the series of storms, Lake Oroville rose to unprecedented water surface elevations which resulted in the use of the emergency spillway for the first time in the history of the dam. The synoptic meteorology conditions that led to these extreme conditions will be presented.