Forecasting the hydroclimatic signature of the 2015-16 El Niño event on the western U.S

Dry conditions in 2013-2016 in the western U.S. were responsible for severe drought and led to an exceptional fire season in the Pacific Northwest. The 2016 winter was forecasted to relieve the southern portion of the West as a result of increased precipitation due to a very strong El Niño signal. We summarize a student forecasting challenge with alternative forecasts made on January 1st, 2016 for the winter hydroclimate across the western U.S. We show that the precipitation forecasts had a large spread and were not very skillful, while anomalously high observed temperatures were forecasted with a higher skill and precision. Strong El Niño sensitivities in dynamical models resulted in an over-prediction of precipitation in the southern part of the West. Our results suggest the need for a more detailed attribution study into the anomalous meteorological patterns of the 2016 El Niño event compared to previous major events.