Enhancements to the Nearshore Wave Prediction System to provide Coastal and Overland Hurricane Wave Guidance

The Nearshore Wave Prediction System (NWPS) is currently being developed to provide on-demand, high-resolution nearshore wave guidance to the coastal forecasters of the National Weather Service (NWS). NWPS features the numerical wave models SWAN and WAVEWATCH III, and is to run logically at Weather Forecast Offices (WFOs) within the Advanced Weather Interactive Processing System (AWIPS). During extra-tropical conditions, wave boundary conditions are received from the National Centers for Environmental Prediction's (NCEP) Global WAVEWATCH III model, surface currents are ingested from RTOFS Global and surge and tide levels are taken from ESTOFS. In response to the devastation caused by Superstorm Sandy (2012), various enhancements have been implemented in NWPS to provide improved coastal wave guidance during tropical cyclone events. Flexible unstructured grids with increased nearshore resolution have been included in order to adequately resolve coastal wave processes. These grids feature both coastal and overland regions, enabling the simulation of waves in areas inundated by storm surge. During a tropical cyclone event, the NWS's National Hurricane Center (HNC) issues a Tropical Forecast/Advisory Message (TCM) featuring a mandated wind forecast. Under these conditions, NWPS is run on the basin-wide domain of NHC's Tropical Analysis and Forecast Branch (TAFB) to produce corresponding wave boundary conditions for coastal WFOs on the U.S. Gulf and East coasts. Due to the high uncertainty in hurricane wind forcing, NHC gives preference to probabilistic surge model guidance using the SLOSH-based P-Surge model. Time-dependent P-Surge fields are ingested in NWPS to provide coastal and overland wave conditions that are consistent with the probabilistic surge advisories issued by NHC's Storm Surge Unit. Field cases will be presented to demonstrate the performance of the enhanced system.