Comparisons of the Experimental Rapid Refresh Forecast System (RRFS) Model With the Operational HRRR for a Variety of Significant Weather Events

As part of the NCEP transition towards a Unified Forecast System, the HRRR group at NOAA/GSL has been testing versions of the Rapid Refresh Forecast System (RRFS) as the FV3-based replacement for the current operational HRRR. The current schedule for operational implementation of the RRFS is in June 2024. The development and testing underway at NOAA/GSL include objective evaluation of RRFS for various retrospective periods chosen to represent different weather regimes. We also have RRFS versions running in real time on the CONUS scale. At the present time the real-time runs extend to varying lengths, but nominally at least two runs per day (initialized at 00 and 12 UTC) goes out to 36-h. These real-time RRFS runs provide an opportunity to make comparisons with the operational HRRR for a variety of weather events. In this presentation we will look at comparisons for some high impact events ranging from winter storms to supercell tornado outbreaks. These subjective comparisons complement ongoing objective scoring of the various forecasts. They also provide a preview of the kind of assessment that operational forecasters will be making before the RRFS is approved to replace the operational HRRR.