The High-Resolution Rapid Refresh (HRRR)

Composite Reflectivity

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.

HRRR Data Archives -
• Google Cloud Platform HRRR archive - native, isobaric, surface - since 2014
  requires installing a program called gsutil, but once that is done it is very straightforward to get one or multiple files. - https://cloud.google.com/storage/docs/gsutil_install
• AWS - Amazon Web Services - HRRR archive - native, isobaric, surface - since 2014
• Univ. of Utah HRRR archive - surface, isobaric - for HRRR-oper and HRRR-experimental
• Python library used to pull HRRR archive data from different cloud archive sources
• NOAA NOMADS archive

News items

• spring 2019 - Experimental HRRRX now running with configuration for HRRRv4 at NCEP in 2020.
• 19 Aug 2017 - Eclipse-ready experimental HRRR/RAP - The ESRL/GSD experimental HRRR and RAP included new code to include the effect on sun radiation from the 21 Aug 2017 eclipse. Eclipse code added to RAPv4/HRRRv3 package. More information is available at eclipse2017.noaa.gov.
• 23 Aug 2016 - HRRRv2 implementation at NCEP/NWS/NOAA, replacing previous HRRRv1.
• July 2016 - HRRR-Smoke model run experimental
• 1 Jan / 10 April 2015 - RAPv3 (Jan) / HRRRv2 (Apr) -ESRL upgrade completed. Graphic summary, changes shaded red.
• 30 Sept 2014 - NCEP Operational Implementation:
  Hourly and sub-hourly graphics and grids available.
  NCEP Release Notes HRRR v1.0.4