Reintegration of Canadian Radar Data into MRMS

There had been an outage of Canadian radar data on the MRMS system since June 5, 2023 when Environment and Climate Change Canada (ECCC) adjusted their scanning strategies with their radar. An operational update to MRMS was completed on November 28, 2023 to adjust for the new scanning strategies in MRMS. All Canadian radars are now available in the MRMS product creation. Further information can be found in the NWS service change notice:

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Update on AutoNowCaster (Removal from MRMS)

The AutoNowCaster (ANC) products will be removed from the operational MRMS system on or about Wednesday, September 6, 2023. This includes the following products: 1) Convective Likelihood, which indicates regions where new storm initiation and/or the growth/sustainment of advecting storms is likely, and 2) Final Forecast, which indicates 60-minute extrapolation of existing storms with reflectivities > 35 dBZ (including growth and decay), and areas where new storms are likely to initiate, with three levels of new storm initiation.

More information on the removal of the ANC applications can be found in this NWS Service Change Notice:

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Canadian Radar Changes and MRMS Outages

On 30 May 2023, NSSL was notified by Environment and Climate Change Canada (ECCC) that the radar scanning pattern used by all Canadian radars will be changing between 5 and 15 June 2023. ECCC will first deploy the change at three radar sites on 5 June 2023. Then, between 12 and 15 June 2023, the other 27 Canadian radars will switch to the new scanning pattern. This scanning pattern means that most elevation angles scanned by the Canadian radars will change. The six bottom-most elevation angles will also have new, extended ranges.

As radars are switched over to the new scanning patterns, they will disappear from the operational MRMS system and from the MRMS products displayed in NSSL MRMS Operational Product Viewer. NSSL is currently working on a patch to the MRMS system that will enable the decoding, processing, and display of the Canadian radars using the new scanning pattern. Once this patch is complete and has been tested, we will coordinate with the National Weather Service to implement the fix in the operational MRMS system. We will provide an update as we learn more about the implications of the scanning changes and have any more specifics to share about the scheduling of an MRMS patch.

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Status of AutoNowCaster in MRMS

The NWS is considering removing the AutoNowCaster (ANC) products from the MRMS suite. They are accepting public comments on the proposed change until March 19, 2023. To submit feedback, please visit this Google form. You can read the full Public Information Statement by visiting this notification page. The NWS is accepting public comments until March 19, 2023.

While this is not a MRMS QPE product, it is important for us to notify MRMS users of this pending discontinuation of these ANC products.

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MRMS v12.2 Operational at the NWS

MRMS v12.2.0 was made operational at NCEP Central Operations for the NWS on 22 April 2022. This update primarily focused on the implementation of the new Canadian S-band radars into the MRMS system. Other updates included improvements to radar quality control, radar QPE, and gauge ingest/metadata.

More details about MRMS v12.2.0 can be found here: Code Updates Page

Operational Product Viewer Web Page:

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MRMS Performance During the Tennessee Flash Flood Event

The tragic flash floods in Tennessee on August 21-22, 2021 unfortunately took the lives of 20 people, as record rainfall and swift waters carried away homes and vehicles. Analysis of the event from operational NWS forecasters noted the extreme precipitation totals within the MRMS system and how its forcing into the FLASH system translated to products signaling the potential catastrophic nature of this event.

An internal evaluation of the MRMS quantitative precipitation estimation (QPE) products first yielded two notable results: 1) the MRMS dual-polarization synthetic QPE was remarkably accurate compared to gauge observations, and 2) it allowed for precise QPE inputs into the FLASH product suite.

Starting with the operational MRMS dual-polarization QPE accumulated for 24-hours, the analysis of 21 August showed a well correlated comparison to both hourly HADS/MADIS gauges as well as daily CoCoRaHS gauges. There was some slight underestimation with accumulations > 6.0 inches, yet the two gauge observations near the highest accumulation totals were well matched to the MRMS QPE (Fig. 1). MRMS QPE for the 24-hour period ending on 1200 UTC 22 August showed an overestimation bias with accumulations < 2.0 inches, but the overall data was also well correlated (Fig. 1).

Fig. 1. Analysis of MRMS dual-polarization QPE ending 1200 UTC on 21 August (left column) and 22 August (right column) with bubble plots (top row) and scatterplots with statistics (bottom row) using hourly and daily gauge observations.

Knowing that the radar-based QPE performed well, one can get a representative analysis with the FLASH product suite without having to worry about QPE biases. The different FLASH products showed a classic signal for a catastrophic event (Fig. 2). The QPE-to-FFG ratio exceeded the guidance needed for bankfull conditions on small channels by a factor of four or more. The average recurrence internal easily maxed out with a 200-year return period, notably for accumulation periods from 3 to 24 hours. The CREST maximum unit streamflow values were also off the chart, signifying the potential for extreme flash flooding.

Fig. 2. Analysis of the following FLASH products at 1300 UTC 21 August 2021: maximum QPE-to-FFG ratio (left), maximum QPE average recurrence interval (center), and CREST maximum unit streamflow (right).

One additional evaluation of the MRMS product suite with the Multisensor QPE (MSQPE) product yielded a third notable result: 3) the performance of the MRMS dual-polarization synthetic QPE was similar to that of the MSQPE, especially for the 24-hour accumulation ending 1200 UTC 21 August (Fig. 3). The bias ratio and correlation between the dual-polarization QPE and MSQPE products were nearly identical on August 21, while there was a reduction in the MAE and RMSE statistics. The MSQPE scheme for August 22 improved all statistics and helped mitigate the overestimation bias seen east of the main precipitation event.

Fig. 3. Comparison of the MRMS dual-polarization synthetic QPE (top row) and MSQPE (bottom row) for the 24-hour accumulation period ending 1200 UTC 21 August (left column) and 22 August (right column). Comparisons were using only daily CoCoRaHS gauges, since they are independent gauge observations for both products.

The final storm-total precipitation yielded a widespread area of rainfall exceeding six inches, with a localized area of 16-20 inches (Fig. 4). The MSQPE values near McEwen, TN matched well with the preliminary rain gauge storm total of 17.02 inches. Overall, it was a successful performance of the MRMS precipitation product suite for this historic event.

Operational MRMS products can viewed on the following public web page:

Fig. 4. Storm total accumulation of the MRMS dual-polarization synthetic QPE (left) and MSQPE (right) for the 48-hour period ending 1200 UTC 22 August 2021.
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MRMS v12.1 Operational at the NWS

Following the successful update of MRMS with the build v12.0, the MRMS v12.1.0 update was implemented on 1420 UTC 24 February 2021 at the National Weather Service. This update contains a series of updates that provide technical improvements to the MRMS system, changes to what is distributed on the NWS Satellite Broadcast Network (SBN), the addition of the Alamosa, CO gap-filling radar, and changes to the Multi-Sensor QPE product latency.

More details about MRMS v12.1.0 can be found here: Code Updates Page

Operational Product Viewer Web Page:

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MRMS v12.0 Operational at the NWS

The anticipated update of the MRMS system to version 12.0 became operational at the National Weather Service at 1330 UTC on 14 October 2020. The MRMS v12.0 build is the largest update to the MRMS hydrometeorological product suite since the initial operating capabilities in September 2014. This build includes a series of scientific advancements ranging from a new dual-polarization synthetic radar QPE to a multi-sensor QPE that gap-fills areas of poor radar coverage.

More details about MRMS v12.0 can be found here: Code Updates Page

Operational Product Viewer Web Page:

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Progress Towards MRMS v12.0 Implementation

The onboarding process for the MRMS version 12.0 update at NCEP Central Operations began in April and is targeting an operational transition by the end of the fiscal year (September 2020). While the onboarding and testing continues, a list of updates for the v12.0 build can be found on the Code Updates page.

The v12.0 build of the MRMS system is the biggest update for the precipitation product suite since the initial operating capabilities back in September 2014. Highlights of the MRMS v12.0 product updates include the following:

  • Dual-polarization synthetic radar QPE with an evaporation correction
  • Advancements to radar and gauge data quality controls
  • A new Multi-Sensor QPE that combines radar-based QPE with gauges, model QPF, and climatologies
  • New MRMS data for Alaska, Hawaii, Guam, and the Caribbean

The MRMS team looks forward to having the new products made available and to continuing their research and development efforts to improve the science of precipitation estimation.

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MRMS Research and Future Plans Presented at AMS100

AMS100 Meeting

Multiple presentations and posters regarding the work being done for the Multi-Radar Multi-Sensor system were presented by OU/CIMMS and NSSL staff at the 100th AMS annual meeting. Topics ranged from a new bright band delineation technique to improving orographic precipitation estimations to the future plans of MRMS. You can view all of the topics presented by going to the 2020 conference presentations page.

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