Rap and HRRR Model/Assimilation System Improvements for Aviation Weather Applications: Latest Upgrades and Ongoing Work

An operational upgrade of the RAP and HRRR model systems at NCEP is planned for August 2016.  This coordinated upgrade (RAP version 3 and HRRR version 2, RAPv3/HRRRv2) includes many enhancements to the data assimilation, model, and post-processing formulations that result in significant improvements to nearly all forecast aspects, including upper-air, surface, cloud and precipitation, and thunderstorms.  Work is also ongoing toward the next NCEP operational implementation (RAPv4/HRRRv3), planned for late 2017 or early 2018.  Additional work is focused testing and refinement in related areas, including a real-time prototype High Resolution Rapid Refresh Ensemble (HRRRE), a post-processing-based HRRR-time-lagged ensemble (HRRR-TLE), a HRRR domain cover Alaska (HRRR-AK), and a Rapidly Updating Analysis (RUA) system. 

In this presentation, a recap of the RAPv3/HRRRv2 upgrade and forecast improvements will be given, followed by a description of the planned improvements for RAPv4/HRRRv3 and an overview of the related work efforts (HRRRE, HRRR-TLE, HRRR-AK, and RUA). Major planned model improvements for the RAPv4/HRRRv3 include, further enhancements to the model physics components (aerosol-aware Thompson microphysics, MYNN PBL scheme, Smirnova land-surface model), testing of a new vertical coordinate, improved terrain treatment, and upgrade to a new WRF version).  The interaction of the various physics modules has been a particular research focus area, with modifications in place that further reduce various physics-related model biases.  Planned data assimilation enhancements include more fully cycling the HRRR model (partial cycling from the RAP two or four times per day), assimilation of additional observations (more satellite data with improved bias control, radar radial velocity data, GOES cloud-top cooling rate data), and upgrade to a new GSI version.   

HRRR time-lagged ensemble products are now being produced in real-time for many variables, with grids being transferred to AWC and other operational centers.  In addition, a full HRRR ensemble was testing in real-time during the spring of 2016, with additional real-time testing scheduled to resume in Nov. 2016.  A brief overview of these efforts will be presented.  Finally, time-permitted, a brief overview of the HRRR-Alaska real-time runs and prototype RUA products will be presented.