How Do Forecasts from WRF-ARW and Stand-Alone Regional FV3 Compare?

In consequence of NOAA’s decision to unify its forecast suite around one model dynamical core, the Finite Volume on the Cubed Sphere (FV3), the current Rapid Refresh and High-Resolution Rapid Refresh operational models, now running as instantiations of the WRF-ARW (Advanced Research Weather Research and Forecast) model, are being converted to run with the FV3 dynamical core. A stand-alone version of FV3 has been developed jointly by the Environmental Modeling Center of NOAA’s National Centers for Environmental Prediction and the Global Systems Division (GSD) of NOAA’s Earth System Research Lab. As of mid-summer 2019, controlled comparisons (same initial and lateral boundary conditions, same physics, very similar domains) of the FV3 and WRF-ARW dynamical cores are being prepared to run at GSD in real time at both hydrostatic scales (13km grid spacing for RAP) and convection-allowing scales (3km grid spacing for HRRR). Our presentation will discuss results of this comparison with emphasis on the HRRR, including forecast examples for various weather scenarios and results of objective verification.