Development of Forcing Engine for Operational Water Prediction System over Hawaii Islands

This study introduces the development of the meteorological forcing engine for the NOAA National Water Model (NWM) over Hawaii islands. The system uses real-time, operational forcing from the NOAA North American Mesoscale Forecast System (NAM) output to drive the analysis and short-range forecasting. The NCEP Global Forecast System (GFS) output is used to construct the forcing for the medium range (0-10 day) forecasts, and the NOAA Climate Forecast System (CFS) provides the forcing for the long range (0-30 day) forecasts. Meteorological input data are regridded to a common 1-km Hawaii domain and selected variables (temperature, humidity, pressure and shortwave radiation) are topographically downscaled to drive the the community WRF-Hydro model. The influences of downscaling on different type/resolution meteorological forcing for different forecasts under different seasons are studied. The impact of downscaling to precipitation field is also investigated. The results are summarized in this presentation.