Verification and Comparison of Storm and Storm-Environment Fields in the HRRR, RRFS, and NSSL MPAS Models

NSSL is exploring the suitability of the NCAR Model Prediction Across Scales - Atmosphere (MPAS-A; hereafter, simply “MPAS”) as the next-generation dynamical core in the NSSL Warn-on-Forecast System (WoFS). To assess strengths and weaknesses of MPAS relative to the existing WoFS dynamical core – the Advanced Research version of the Weather Research and Forecasting model (ARW) – and the UFS-based Finite-Volume Cubed-Sphere model (FV3), we are comparing forecast output among five deterministic models: the ARW-based High-Resolution Rapid Refresh (HRRR); EMC’s deterministic, CONUS-domain prototype of the FV3-based Rapid Refresh Forecast System (RRFS) that is tentatively scheduled to replace the HRRR and several other mesoscale model systems in 2024; and three regional MPAS models developed and run by NSSL. The three MPAS models differ only in their initializations and microphysics schemes: the MPAS-HT-NSSL is initialized from the HRRR and uses the Thompson scheme; the MPAS-RT-NSSL is initialized from the RRFS and uses the Thompson scheme; and the MPAS-HN-NSSL is initialized from the HRRR and uses the NSSL two-moment scheme. Comparing the MPAS-HN-NSSL and MPAS-HT-NSSL will allow us to test our hypothesis that the NSSL two-moment microphysics produces better thunderstorm forecasts in the MPAS, as it does in the ARW-based WoFS. Comparing the MPAS-RT-NSSL and RRFS, and the MPAS-HT-NSSL and HRRR, will illuminate the systematic impacts of the different dynamical cores given the similarity of the physics packages used in the models.

The project team is using a variety of methods to compare forecast performance and systematic differences among the five models. In this presentation, we use probability-matched composite means to visualize systematic differences in storms and near-storm environments, then compare errors in surface variables and sounding-derived parameters among the models using radiosonde and Automated Surface Observing Systems observations for verification.