Long Range Streamflow Forecasting Using El Nino-Southern Oscillation Indicators

Hydrologists and water resource planners in the Pacific Northwest region of the United States are under pressure from competing water users to make long-range forecasts of streamflow. At present, long-range streamflow forecasts are not offered. Yet in the Pacific Northwest, a significant lag relationship exists between (El Nino-SouthernOscillation) and streamflow. Using this lag relationship, this study proposes to extend the prediction of spring-summer runoff in the Pacific Northwest from the current 1- to 3-month lead time to a 3- to 7-month lead time. This study looks at the Columbia River basin, where testing is being conducted on a long-range seasonal streamflow forecasting model that uses, as predictors, persistence in streamflow along with two El Nino-SouthernOscillation indicators: the Southern Oscillation Index and the Wright sea surface temperatures. A probabilistic streamflow forecast is made from an optimal linear combination of persistence, Southern Oscillation Index linear discriminant analy...