A Status Update for the NAMRR, an Hourly-Updated Version of NAM Forecast System

The North American Mesoscale Rapid Refresh system (NAMRR) is a developmental, hourly-updated version of the North American Mesoscale Forecast System (NAM) and its data assimilation system. The current version of the NAM, recently upgraded in August 2014, provides 84 hour forecasts 4 times per day at 00, 06, 12, and 18 UTC. The NAM Data Assimilation system currently performs an atmospheric analysis only every 3 hours and on its 12 km North American domain - there is no cycling of its nested domains. The NAMRR, in contrast, features an hourly forecast and assimilation cycle. Furthermore, the NAMRR also features a data assimilation cycle for its 3 km CONUSnest domain in addition to its North American 12 km domain. All forecasts from the NAMRR are a minimum of 18 hours in length, and to maintain compatibility with the current operational NAM, 84 hour forecasts are issued at 00, 06, 12, and 18 UTC. The NAMRR also plays a significant role in the future development of the North American Rapid Refresh Ensemble and High Resolution Rapid Refresh Ensemble systems (NARRE and HRRRE, respectively). NAMRR will form the foundation of one half of this system, while the Rapid Refresh and High Resolution Rapid Refresh (RAP and HRRR) systems will form the basis of the other half of NARRE and HRRRE, respectively. It is upon these rapidly updating analysis systems that a future rapid update ensemble prediction system will be constructed. Therefore, the continued development of the NAMRR is an important step toward the realization of both the NARRE and HRRRE systems. A description of the NAMRR, applications to case studies, and a discussion of ongoing and future work will be presented.