Merging medium-range weather forecasts and seasonal climate outlooks to improve seasonal hydrologic prediction

Most hydrologic forecasting approaches for seasonal to interannual lead times incorporate seasonal-scale climate signals but ignore weather to medium-range climate forecasts. At certain times of year, varying by region, weather in the first few weeks of a season have a disproportionate influence on seasonal hydrologic outcomes, which argues for the explicit consideration of shorter range weather/climate predictions. The utility of medium-range hydrologic outlooks for water and energy management also motivates this work. This presentation explores potential benefits from imbedding medium range weather forecasts into ensemble streamflow predictions, using a parametric scaling approach. Results for retrospective cases at locations in the western U.S. are presented.