“…Proactive water management has become critical for many regions in the world that are susceptible to water stress asso-ciated with the intensification of the water cycle. Paradoxically, although we have seen important technological advances, including increased computing power, the broader availability to climate reanalysis, forecasts and reforecasts, and more complex process-based hydrologic models (Pagano et al, 2016), the skill of operational seasonal runoff predictions in the US, termed water supply forecasts (WSFs), has shown little or no improvement over time (e.g., Pagano et al, 2004;Harrison and Bales, 2016). Hence, there is both a scientific and practical need to understand the potential of new datasets, modeling resources, and methods to accelerate progress towards more skillful and reliable operational seasonal streamflow forecasts.…”