Past Code Updates

This page looks at past code updates of the MRMS system prior to the current operational version (v12.3 as of 22 July 2025).

MRMS v12.2.6 Update to NCO
Implementation Date: 28 November 2023

Highlights of Changes Made to the MRMS QPE Product Suite:

  • The radars maintained by Environment and Climate Change Canada (ECCC) underwent a change to adjust their scanning strategies in June 2023. This ultimately led to a dropout of Canadian radar data into the MRMS product creation since 5 June 2023. This build accounted for the new ECCC radar scanning strategies.

More information on this build can be found through the following links:

MRMS v12.2.0 Update to NCO
Implementation Date: 22 April 2022

Highlights of Changes Made to the MRMS QPE Product Suite:

  • Removing the Canadian C-band (single-pol) radars and replacing them with the new S-band (dual-pol) radars
  • Updated radar quality control algorithms for the Canadian S-band radars along with updates for removal of bad data due to hardware issues, wind farm clutter mitigation, and errors with Kdp derivations
  • Improvements to bright band identifications, removal of false convective identifications, and improved QPE calculations
  • Corrected grid coordinates and gauge metadata for Hawaii domain
  • Improved gauge processing and reference data to allow for more gauges to be integrated into MRMS

More information on this build can be found through the following links:

MRMS v12.1.0 Update to NCO
Implementation Date: 24 February 2021

Highlights of Changes Made to the MRMS QPE Product Suite:

  • Changes to products that are available on the NWS Satellite Broadcast Network (SBN) that include the following:
    • Added to SBN (CONUS): FLASH product suite (visit the FLASH site for more information: https://inside.nssl.noaa.gov/flash/)
    • Added to SBN (Alaska and Hawaii): Composite reflectivity and precipitation product suite
    • Removed from SBN: Radar quality index (RQI), seamless hybrid scan reflectivity, probability of warm rain, and various reflectivity products
  • Ending distribution of MRMS binary-formatted products
  • Addition of Alamosa, CO radar to 2-D mosaics and improved QPE products
  • Reduced latency for Multi-Sensor QPE Pass 1 from 60 minutes to 20 minutes; Reduced latency for Multi-Sensor QPE Pass 2 from 120 minutes to 60 minutes
  • Addition of radar-only QPE accumulation since 1200 UTC product
  • Other technical and feed changes (e.g., XMRG product updates, modifications to background values, updated NetCDF and GRIB2 reference data)

MRMS v12.0 Update to NCO
Implementation Date: 14 October 2020

Highlights of Changes Made to the MRMS QPE Product Suite:

  • New dual-polarization synthetic radar QPE that will replace the reflectivity-only approach (also used as new QPE forcing for FLASH system)
  • Application of an evaporation correction algorithm to reduce light precipitation overestimations and false light precipitation
  • Mitigation techniques for WSR-88D issues along with updates to blockage references files (including Canadian radars) and wind farm tables
  • Updates to Radar Quality Index to better account for terrain and spatial variations in the freezing level height; RQI is also accumulated in time
  • New 15-min radar-based accumulation (at a 15-min cadence)
  • New Radar QPE Accumulation Quality Index (RAQI)
  • New Pass 1 and Pass 2 structure to create gauge-derived products with less latency and later with increased gauge observations
  • Multi-sensor QPE scheme using gauges and model QPFs to fill radar coverage gaps
  • MRMS and FLASH product suites for new oCONUS domains: Alaska, Hawaii, Caribbean, and Guam
  • Canadian radars (C-band only) included in raw and QC’d 2-D composite reflectivity mosaics

MRMS v11.6.1 Update to NCO
Implementation Date: 27 November 2018

Very few updates were relevant to the MRMS QPE product suite; however, other updates were made operational that affect other products and output within MRMS. This includes the following:

  • Increase AutoNowCaster product resolution from 5 km to 1 km
  • Additional products converted to SPC NIDS
  • Modifications to colormaps for RIDGE2 GeoTIFF

The biggest update for MRMS v11.6.1 was the update of the FLASH GRIB2 compression and having the FLASH data available via web services and LDM. For more information on FLASH, please visit https://inside.nssl.noaa.gov/flash/.

MRMS v11.5.4 Update to NCO
Implementation Date: 17 May 2018

Highlights of Changes Made to the MRMS QPE Product Suite:

  • Radar Ingest/QC/Mosaics: New logic to handle the new NWS WSR-88D radar volume coverage patterns (VCPs)
  • Radar Quality Index: Refined logic for better spatial continuity between individual radar sites and representation of quality coverage.
  • Surface Precipitation Type: Discontinuities for classifying tropical precipitation types were removed.
  • Gauge Ingest and Product Latency: The gauge feed into MRMS now includes MADIS along with HADS. The latency time to wait for gauges has been reduced from 70 minutes to 50 minutes in order to generate timely products for end-users.
  • Gauge Quality Control: Changes were made to the nearest neighbor gauge-grid cell pairing and to the outlier equations; Additional logic was added to accommodate future use of satellite and model fields for QC.