February 28, 2019
NOAA's National Water Model: An Overview of Model Activities and Related Initiatives
Established with an initial implementation into National Weather Service (NWS) operations just over two years ago, the National Water Model (NWM) provides seamless 24x7 guidance on streamflow conditions and other water budget fields. Based on the community WRF-Hydro software architecture, it has been rapidly upgraded via a partnership between NWS/OWP, NCAR and NWS/NCEP. Version 2.0, scheduled for implementation in mid-2019, will build on prior capabilities to provide vital hydrologic guidance to NWS River Forecast Centers (RFCs), Weather Forecast Offices, NCEP Centers, the Federal Emergency Management Agency and other Federal, private and academic end users. It will feature upgrades including use of RFC-based precipitation in a new extended analysis cycle, the addition of a Hawaii domain, a medium range ensemble configuration, and improved forcing downscaling and parameter calibration. One of the other major upgrades initiated in V2.0 centers on improved code modularity. This advance is significant in that it underlies an intensive strategy to establish a broad NWM development community. It is envisioned that the NWM will serve as a common platform for water research and operations. By drawing innovation from across a broad spectrum of interests, the system will support a variety of research and applications beyond its core NWS operational forecasting mission. Beyond community development, NWM V2.0 and subsequent versions will provide the foundation needed to support a variety of additional activities within the NWS and broader hydrologic community. These include a machine learning-based enhancement to better capture the impact of stream regulation, a model extension to simulate combined impact of freshwater and coastal flooding, and an improved shallow groundwater model. Hyper-resolution modeling will support the ability to model flooding in areas of urban coverage or high terrain and NWM-based regional flood inundation mapping efforts will expand to the continental scale to support emergency responders across the Nation.