Lessons Learned from Seven Years of Water Year Outlooks in California

Wednesday, April 22, 2015
Klaus Wolter, University of Colorado at Boulder, CIRES, Boulder, CO, United States
Since 2008 the California Department of Water Resources (DWR) has supported my annual fall briefing to provide best-available guidance for California water agencies on whether the coming water year might be wet, dry, or ‘near-normal’. At NOAA’s Climate Prediction Center (CPC), the primary source of predictive skill at seasonal time scales is presently the El Nino-Southern Oscillation (ENSO) cycle. Unfortunately, this has not translated into operational winter-time forecast skill for this part of the US. My presentation explores what other factors were considered to improve on CPC’s record. While my original efforts were focused on finding best possible analog years for the forecast situation at hand, I have now developed a statistical forecast model that has been put to the test for three years running. This presentation will include an evaluation of forecast skill for the last seven years, skillful predictors beyond ENSO (Niño 3.4 SST), and current areas of research to improve forecasts further.