Regional Ocean Modeling System (ROMS) 7-day, 3-hourly forecast for the region surrounding the main Hawaiian Islands at approximately 4-km resolution. Boundary conditions provided by the global, 1/12-degree (~9-km) HYbrid Coordinate Ocean Model (HYCOM). Atmospheric forcing generated by the Weather Research and Forecasting (WRF) model for the region surrounding the main Hawaiian Islands (wrf_hi) at approximately 6-km resolution. Tide forcing uses the Oregon State University (OSU) Tidal Prediction Software (OTPS) TOPEX/Poseidon global inverse solution (TPXO) to derive barotropic tidal elevation and velocity. Data are assimilated over the previous 3 days using all available observations to improve the model estimate of current ocean state (its nowcast) before forecasts are run. Assimilated observations may include satellite-based sea surface temperatures from MODIS, AVHRR, or OSTIA; satellite-based sea surface height from AVISO; surface currents from PacIOOS high-frequency radios (HFR); and in-situ water temperature and salinity profiles from ARGO floats and ocean glider autonomous underwater vehicles (AUV). While considerable effort has been made to implement all model components in a thorough, correct, and accurate manner, numerous sources of error are possible. As such, please use these data with the caution appropriate for any ocean related activity.