The High Resolution Rapid Refresh (HRRR): The Operational Implementation

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. This operational implementation required a sequence of coordinated efforts between the researchers at Earth System Research Laboratory Global Systems Division (ESRL/GSD) and counterparts at NCEP's Environmental Modeling Center (EMC) and NCEP Central Operations (NCO). In this presentation we will discuss this transition including establishing required input data feeds on the NCEP high performance computer such as the Multi-Radar/Multi-Sensor (MRMS) System, porting of model code from the research to the operational computer, optimization of model code to meet the operational runtime and resource requirements, establishing a real-time parallel HRRR run on the operational computer system, validation of the transitioned code and final user evaluation. A highlight of this process was establishing a new paradigm for operational implementations that consolidated efforts by EMC and NCO to establish the real-time parallel runs on the operational system relatively early in the transition process and increase the efficiency of the implementation. Finally, 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.