2.3      The final Rapid Refresh and High-Resolution Rapid Refresh operational implementation and the bridge to a Unified Forecast System.

Alexander, Curtis, David Dowell, Steve Weygandt, Stan Benjamin, National Oceanic and Atmospheric Administration (NOAA), Ming Hu, Tanya Smirnova, Joe Olson, Jaymes Kenyon, NOAA and University of Colorado/Cooperative Institute for Research in Environmental Sciences (CIRES), Georg Grell, NOAA, Eric James, NOAA and CIRES, Haidao Lin, NOAA and Colorado State University/Cooperative Institute for Research in the Atmosphere (CIRA), Terra Ladwig, Jeff Duda, NOAA and CIRES, John Brown, Trevor Alcott, NOAA, and Isidora Jankov, NOAA and CIRA

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 evaluated as part of this upgrade including improved representation of sub-grid clouds, gravity-wave drag enhancements, new land surface/lake model capabilities, inclusion of an implicit-explicit vertical advection scheme, and use of an hourly-cycled storm-scale ensemble analysis system. This final configuration of these GSI and WRF-ARW -based systems will serve as an operational baseline for the transition to regional convection allowing applications in a Unified Forecast System.