The 2014 HRRR and Rapid Refresh: Hourly Updated NWP Guidance from NOAA for Aviation, Improvements for 2013-2016

This paper will describe a yearly sequence of planned NOAA's upgrades to the 13km Rapid Refresh and 3km High-Resolution Rapid Refresh (HRRR) atmospheric weather prediction models In support of aviation and other short-range forecast applications. NOAA completed a transition of an initial version of the hourly updated 13km Rapid Refresh (RAP, North American domain) in May 2012 from NOAA/ESRL to NOAA/NCEP, and now nears implementation at NCEP of RAP version 2 and the 3km HRRR (nested within and initialized primarily by RAP).

First, 2013 changes made to HRRR and RAP version 2, run (as of Aug 2013) at NOAA/ESRL to improve forecasts of convective storms and other aviation hazards, will be described (including introduction of ensemble data assimilation and 3km radar assimilation). The key results for aviation applications are: 1) much improved forecasts of convective storms and winter precipitation due to data assimilation improvements, 2) improved near-surface forecasts due to introduction of the MYNN-Olson boundary-layer scheme and a 9-level soil model, and 3) reduction of latency in HRRR model forecast production through an accelerated 3-km analysis and more efficient post-processing. The beneficial effects of these changes on convection, near-surface/terminal, ceiling and visibility forecasts will be presented. New graphical products based on the HRRR including sudden wind change and temporal consistency of thunderstorm prediction will be shown.

An update on status for the RAPv2 and HRRR implementations at NCEP will also be presented.

For 2014, development is now underway for improvements in radial wind and reflectivity assimilation cloud assimilation, and in boundary-layer, cloud microphysics and other parameterizations for implementation into the 2014 versions of RAP and HRRR to be run initially at ESRL prior to their subsequent implementation in later upgrades at NCEP.

Finally, ongoing development toward ensemble-based hourly updated weather guidance will be presented, including latest extensions of the time-lagged-ensemble-based HRRR Convective Probabilistic Forecast (HCPF) and the upcoming North American Rapid Refresh Ensemble (NARRE). The NARRE will be based on a true ensemble (6 members planned) with both WRF-ARW and NMMB dynamic core members with co-development by NOAA/ESRL and NOAA/NCEP/EMC. The NARRE will facilitate the subsequent implementation of hourly updated storm-scale CONUS-wide numerical forecasts (as computer resources become available) in the HRRR Ensemble (HRRRE).