The Yangtze River has been subject to heavy flooding throughout history, andin recent times severe floods such as those in 1998 have resulted in heavy lossof life and livelihoods. Dams along the river help to manage flood waters, andare important sources of electricity for the region. Being able to forecasthigh-impact events at long lead times therefore has enormous potential benefit.Recent improvements in seasonal forecasting mean that dynamical climate modelscan start to be used directly for operational services. The teleconnection fromEl Ni\~no to Yangtze River basin rainfall meant that the strong El Ni\~no inwinter 2015/2016 provided a valuable opportunity to test the application of adynamical forecast system. This paper therefore presents a case study of a real time seasonal forecastfor the Yangtze River basin, building on previous work demonstrating theretrospective skill of such a forecast. A simple forecasting methodology ispresented, in which the forecast probabilities are derived from the historicalrelationship between hindcast and observations. Its performance for 2016 isdiscussed. The heavy rainfall in the May-June-July period was correctlyforecast well in advance. August saw anomalously low rainfall, and theforecasts for the June-July-August period correctly showed closer to averagelevels. The forecasts contributed to the confidence of decision-makers acrossthe Yangtze River basin. Trials of climate services such as this help topromote appropriate use of seasonal forecasts, and highlight areas for futureimprovements.
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