5.1 Progress in High-Resolution Rapid Refresh (HRRR) Deterministic and Ensemble Development for Convective Hazard Forecasts

Tuesday, 23 October 2018: 11:00 AM
Pinnacle room (Stoweflake Mountain Resort )
Curtis R. Alexander, NOAA/ESRL/GSD, Boulder, CO; and D. C. Dowell, T. Alcott, T. Ladwig, M. Hu, J. Duda, G. Ge, T. G. Smirnova, J. B. Olson, J. Kenyon, J. Beck, I. Jankov, E. P. James, S. S. Weygandt, S. Benjamin, J. M. Brown, G. Grell, J. A. Hamilton, M. B. Smith, and D. D. Turner

Development of the Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR) model forecast systems started a little more than a decade ago. These models were designed with community-based components including Gridpoint Statistical Interpolation (GSI) for observational data assimilation, a specially configured version of the Advanced Research WRF (ARW) model, and unified post-processing (UPP).

With the adoption of community-supported model components such as GSI, WRF-ARW and UPP, frequent contributions to the RAP and HRRR development have been possible, and as such, a more agile model development paradigm has been established with rapid prototyping for evolutionary upgrades to the RAP and HRRR including use of real-time experimental forecasts that permit operational forecaster feedback. This paradigm and close coordination with the National Center for Environmental Prediction (NCEP) Environmental Modeling Center (EMC) has facilitated a two-year research-to-operations (R2O) transition cycle for the RAP/HRRR between their operational inceptions in 2012/14 and present. We have now concluded the third and fourth R2O cycles of the HRRR and RAP respectively with another transition cycle planned for completion by mid-2020 that will include a HRRR storm-scale ensemble analysis capability, and eventually, ensemble prediction.

This presentation will review highlights of the RAP/HRRR and HRRR ensemble development including a look towards 2020 and eventual incorporation in an operational unified rapid refresh forecast system by 2022. Forecast skill improvements related to specific enhancements in RAP/HRRR WRF-ARW numerics, physical parameterizations and associated data assimilation in the 2018 and 2020 packages with be presented with a focus on convective hazards.

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