This research will address the overarching question of whether observed past climate trends have induced sufficient non-stationarity in climate and hydrologic systems in the western US to alter their predictability, which has consequences for water management. Key question include the following: When and where in the western US are hydroclimate trends and/or decadal variability leading to systematic biases in statistical and model-based waters supply forecasts? What practical adjustments can be made to current forecasting approaches to make seasonal water supply forecasts robust in the face of such phenomena? In particular, can hydrologic sensitivities to temperature be accounted for by leveraging operational temperature forecasts as streamflow predictors or weighting factors in conventional seasonal forecasting procedures? What are the marginal benefits of improvements in seasonal streamflow predictions for water management in the Upper Rio Grande River basin?