NOAA’s National Water Model Version 4.0: Leveraging the NextGen Framework to Improve Hydrologic Operations

With the adoption of the Next Generation Water Resources Modeling Framework (NextGen), the National Water Model (NWM) is poised to undergo a transformational upgrade to version 4.0, with wide-reaching operational impacts. Currently at version 3.0, the NWM provides 24x7 guidance for streamflow and other hydrologic states and fluxes used by NWS River Forecast Centers, the Federal Emergency Management Agency and other government entities, along with academic and commercial sectors. It has been rapidly upgraded through seven versions via a partnership between the NWS Office of Water Prediction (OWP), the National Center for Atmospheric Research (NCAR) and the National Centers for Environmental Prediction (NCEP). Building on knowledge gained via analysis and forecasting with the current framework, the NWM will soon shift from underlying use of the WRF-Hydro framework, to use of the Next Generation Water Resources Modeling Framework (NextGen).

Under development by OWP in collaboration with its federal and academic partners, NextGen is a model-agnostic, standards-based, open-source, water resources model interoperability software framework, designed to speed the R2O pathway in water prediction. It is being purpose-built with a design that supports execution of different model formulations and process modules in different portions of the simulation domain, standardized connection points for community-authored modules, a low overhead for developers, and an architecture for execution on laptops to supercomputers. Each of these elements will accelerate improvements in model skill and responsiveness to the needs of government, private and academic end users.

Use of the NextGen framework for NWS operations is targeted for 2026, with the release of version 4.0 of the National Water Model. This presentation will focus on how major foundational elements of NextGen--the formulation selection and parameter optimization environment, forcing pre-processor, data assimilation components, precipitation and energy partitioning modules, routing module, coastal modules and hydrofabric--will come together to form a robust, performant, operations-oriented configuration. Overall benefits to NWM operations will be discussed as will a timeline for development and implementation.