An Update on the NOAA National Water Model and Related Activities

The National Weather Service (NWS) Office of Water Prediction (OWP), in conjunction with the National Center for Atmospheric Research (NCAR) and the NWS National Centers for Environmental Prediction (NCEP) recently implemented version 1.1 of the National Water Model (NWM) into operations. As with the initial version implemented in 2016, this model is an hourly cycling uncoupled analysis and forecast system that provides streamflow for 2.7 million river reaches and other hydrologic information on 1km and 250m grids. The NWM provides complementary hydrologic guidance at current NWS river forecast locations and significantly expands guidance coverage and type in underserved locations.

With the upgrade to Version 1.1, fundamental hydrologic building blocks are now in place which enable work on several capabilities which are key to hydrologic stakeholders: 1) CONUS-wide flood inundation mapping, 2) Coastal coupling to support joint freshwater/estuary/ocean modeling, 3) Hyper-resolution modeling to capture hydrologic processes in urban environments and areas of high terrain relief, and 4) Machine learning-based simulation of reservoir processes. Each of these hydrologic capabilities addresses a current gap in operational hydrologic forecasting and emergency response. While local versions are currently available, a national flood inundation map will enable coordinated cross-border response. Coastal coupling will likewise enable improved emergency response, via accurate simulation of the additive impacts of freshwater and storm surge flooding. Simulations will also be improved via application of a hyper-resolution nested modeling approach, which will resolve the fine-scale processes that impact flooding in urban and mountainous environments. And lastly, streamflow simulations within each of the preceding applications will benefit from improved simulation of water management at modeled reservoirs. While leveraging the NWM, each of these activities will be driven by cross-agency collaboration.

This presentation will provide an overview of recent and planned NWM upgrades, along with updates on the four hydrologic activity areas above.