The High-Resolution Rapid Refresh (HRRR)

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The HRRR is a NOAA real-time 3-km resolution, hourly updated, cloud-resolving, convection-allowing atmospheric model, initialized by 3km grids with 3km radar assimilation. Radar data is assimilated in the HRRR every 15 min over a 1-h period adding further detail to that provided by the hourly data assimilation from the 13km radar-enhanced Rapid Refresh .
    HRRR implementations at NCEP
  • HRRRv1 - 30 Sept 2014
  • HRRRv2 - 23 Aug 2016
  • HRRRv3 - 12 July 2018
  • HRRRv4 - 2 Dec 2020
    Information here in HRRRv4/RAPv5 summary - Jan 2020

HRRR Colorado Labs Award video - a 2-minute layperson-level description on the HRRR from late 2015 and why it is important. (October 2015)
HRRRv4/RAPv5 .

    Key features for HRRRv4:
  • improved cloud representation for boundary-top clouds, especially for shallow cold-air layers with cold-air retention
  • better cloud bands (snow squalls, hurricane bands, lake-effect bands)
  • 3km ensemble data assimilation for improved storm prediction for 1-12h
  • inline smoke prediction
  • improved lake temperatures
  • Extension to 48h forecast every 6h.

HRRR Ensemble (HRRRE) prediction - documentation as of March 2020
2022 HRRR description - Dowell et al 2022
HRRRv2 physics description in Benjamin et al. 2016, A North American Hourly Assimilation and Model Forecast Cycle: The Rapid Refresh. Mon. Wea. Rev., 144, 1669-1694.

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