Prediction of Extreme Precipitation Associated with Landfalling Tropical Cyclones using the Geophysical Fluid Dynamics Laboratory (GFDL) fvGFS Model

The 2017 Atlantic hurricane season was very active, producing three major hurricanes that made landfall in the US, with Hurricane Harvey causing the most damage and producing the largest rainfall amounts. The focus of this project is to assess the forecasting skill of extreme precipitation associated with Hurricane Harvey and other 2017 Atlantic tropical cyclones using quantitative verification methods. The NOAA Geophysical Fluid Dynamics Laboratory (GFDL) has developed a Finite Volume Global Forecast System (fvGFS), an improved version of the operational GFS with an upgraded dynamical core and microphysics, and this project verifies the fvGFS forecasts of precipitation against the National Center for Environmental Prediction (NCEP) Stage IV data. The National Center for Atmospheric Research (NCAR) Meteorological Evaluation Tools (MET) verification package is used to quantitatively assess the forecast skill. Using MET, the 13-km fvGFS forecast skill is compared against the skill of two operational models, the 13-km GFS and 3-km NAM. The MET skill metrics considered include FSS, ETS, RMSE and BIAS for different precipitation thresholds which will provide the foundation for the quantitative analysis.