Implementing the SWAN wave model at three east coast National Weather Service offices

The National Weather Service (NWS) Weather Forecast Offices (WFO) located in Wakefield, VA, Newport, NC and Wilmington, NC implemented the Simulating WAves Nearshore Model (SWAN) into operations during 2009 in conjunction with the University of North Carolina at Chapel Hill, the United States Army Corps of Engineers Field Research Facility (FRF) in Duck, NC, and NWS WFO Eureka, CA. The SWAN model was coupled to the NWS Graphical Forecast Editor by WFO Eureka in 2005 in an effort to produce gridded nearshore ocean wave analyses and forecasts driven by value-added, forecaster-created wind fields. This method has proven successful in producing wave forecasts that are physically consistent with the NWS wind forecast. Additionally, SWAN better resolves wave patterns around complex coastlines compared to the present form of the widely used NOAA Wavewatch III model given its superior resolution and near shore physics. SWAN thus provides reliable and mission critical guidance to NWS forecasters given the vast majority of marine traffic which occurs in the nearshore zone.

Several upgrades have been made to the SWAN model over the last few years which have recently been incorporated into operations at the East Coast NWS offices involved in this project. Specifically, the ability to use boundary conditions from the North Atlantic Hurricane WW3 model, improved spectral time series, vector and validation output, and an improved wave system tracking methodology have been implemented. These upgrades, operational examples including verification, and data limitations will be discussed. Finally, a brief description of how the model is helping NWS meet societal demands for nearshore wave information and future goals will be presented.