The High-Resolution Rapid Refresh (HRRR): The Operational Implementation and Future Direction with the Aviation Community

The 3-km convective-allowing High-Resolution Rapid Refresh (HRRR) is an hourly updating weather forecast model that use a specially configured version of the Advanced Research WRF (ARW) model and assimilate many novel and most conventional observation types on an hourly basis using Gridpoint Statistical Interpolation (GSI). Included in this assimilation is a procedure for initializing ongoing precipitation systems from observed radar reflectivity data, a cloud analysis to initialize stable layer clouds from METAR and satellite observations, and special techniques to enhance retention of surface observation information. The HRRR is run hourly out to fifteen forecast hours over a domain covering the entire conterminous United States using initial and boundary conditions from the hourly-cycled RAP and is available in real-time to operational forecasters in both the private and public sectors. The HRRR provides unique convective-scale forecast guidance with high spatial and temporal resolution leveraging both hourly updates and a sub-hourly output interval.

During 2014, the HRRR was transitioned, for the first time, from a real-time experimental research model into the operational NCEP production suite. In this presentation, we will provide an overview of the differences between the operational NCEP HRRR and the experimental version running at ESRL (that will be used to test future upgrades to the NCEP HRRR) including the benefits of an operational model with a higher level of availability and faster delivery of HRRR forecast products to downstream users. We will review the performance of 2013-2014 HRRR forecasts with an emphasis on warm-season convection in real-time and retrospective runs. We will also preview the development of the 2015 HRRR forecast system and the scheduled upgrade to the NCEP HRRR version 2 with a focus on improving the data assimilation (including radar observations) at the 3-km scale to further reduce convective-scale “spin-up” in the first few forecast hours and enhancement in model dynamics and physics including shallow convective parameterization to improve the timing of convective initiation in weakly-forced weather regimes. Finally, we will discuss the development of time-lagged ensemble convective probabilities produced from HRRR runs and preview more formal storm-scale ensemble efforts for applications in tactical and strategic decision making in the aviation community.

This research is partially in response to requirements and funding by the Federal Aviation Administration (FAA). The views expressed are those of the authors and do not necessarily represent the official policy or position of the FAA.