Predictability and Prediction of Southern California Rains during Strong El Niño Events: A Focus on the Failed 2016 Winter Rains

AbstractThe failed Southern California (SCAL) winter rains during the 2015/16 strong El Nino came as a surprise and a disappointment. Similarities were drawn to very wet winters during several historical strong El Nino events, leading to heightened expectations that SCAL’s multiyear drought would abate in 2016. Ensembles of atmospheric model simulations and coupled model seasonal forecasts are diagnosed to determine both the potential predictability and actual prediction skill of the failed rains, with a focus on understanding the striking contrast of SCAL precipitation between the 2016 and 1998 strong El Nino events. The ensemble mean of simulations indicates that the December–February 2016 winter dryness was not a response to global boundary forcings, which instead generated a wet SCAL signal. Nor was the extreme magnitude of observed 1998 wetness entirely reconcilable with a boundary-forced signal, indicating it was not a particularly precise analog for 2016. Furthermore, model simulations indicate the...