The Final Rapid Refresh and High-Resolution Rapid Refresh Operational Implementation

The next and final update to the deterministic Rapid Refresh, version 5 (RAPv5), and High-Resolution Rapid Refresh, version 4 (HRRRv4), is currently scheduled for an operational implementation in early-mid 2020. Numerous physics, dynamics and data assimilation changes are being included as part of this upgrade. This presentation will discuss the scope of this implementation including (1) coupling to the Finite Volume Community Ocean Model (FVCOM) with lake hydrodynamics for improved forecasts in the Great Lakes region, (2) wildfire-driven smoke forecasts including feedback to the shortwave radiation, (3) storm-scale ensemble data assimilation and (4) forecast length extensions for selected forecast cycles towards 48 hrs. The presentation will also highlight RAP/HRRR physics suite enhancements including improved representation of sub-grid clouds in the boundary-layer scheme, gravity-wave drag enhancements and new land surface/lake model capabilities. Modifications to the RAP/HRRR (WRF-ARW) numerics including reduced 6th order filtering and inclusion of an implicit-explicit vertical advection scheme for more accurate depiction of extreme vertical velocities at larger time steps will also be discussed. Finally, inclusion of an hourly-cycled storm-scale ensemble analysis system will be presented with demonstrated improvements to convective forecasts. Additional datasets for assimilation will also be highlighted. This final configuration of these GSI and WRF-ARW-based RAP/HRRR model systems will serve as an operational baseline for the transition to a regional convection allowing application in a Unified Forecast System, known as the Rapid Refresh Forecast System (RRFS) and this transition will be described.