Comparing WRF-ARW and FV3 SAR forecasts for Warn-on-Forecast applications

The Finite Volume Cubed Sphere (FV3) model was chosen by NCEP as the common dynamic core for the use in the proposed Unified Forecast System (UFS), a framework which will streamline the operational forecast suite across multiple predictive scales. To help realize this goal, a stand-alone regional (SAR) version of the FV3 has been developed through multi-laboratory (NSSL, GSD, EMC, and NCAR) collaboration. This configuration of the FV3 is intended to be used across scales, from hydrostatic (~13 km) to convection-allowing (~3 km) horizontal grid spacing. To test FV3 forecasts of severe weather and its antecedent environment at convection-allowing scales, we will perform controlled comparisons (using same initial and lateral boundary conditions with similar physics and domains) between the CCPP-enabled SAR-FV3 and the Advanced Research Weather Research and Forecasting (WRF-ARW) model. The initial conditions for the SAR runs will be obtained from NSSL experimental Warn-on-Forecast (WoF) domain forecasts from 2018 and 2019 using the ARW-WRF system. Our results will focus on comparisons of specific forecasts as well as on objective verification analyses.