Rapid Refresh Forecast System (RRFS)


Serious Issues with the RRFS

Posted Monday 03/25/24 @ 5:33 PM — While the RRFS model development (now in version 0.8.5) continues to progress, the lead scientists in model’s development have come to the recent realization that the FV3 core of the model may not allow it to reach the level of accuracy needed for proper prediction of convection (thunderstorms).

Specifically the current experimental RRFS over-predicts areal coverage of convective precipitation and over-predicts amount of precipitation, especially when forecast amounts are over an inch. It does not do as well as the HRRR or in some cases, the NAM-NEST for accurate forecast of thunderstorms.

These issues apparently can’t be solved due to inherent limitations of the FV3 dynamic core in this non-hydrostatic mesoscale model. (The FV3 core is successfully used in the current GFS model, a hydrostatic model.)

An extensive review and discussion of the experiments leading to this realization can be found in this paper published Dec 2023.

Unfortunately, years have already been spent in development using the FV3 and a change away from the FV3 core may be prohibitively difficult. It appears that the NOAA decision to standardize and unify model development using the FV3 core was a poor decision.

An alternate approach, using the MPAS (Model for Prediction Across Scales) is now planned for RRFS version 2.0. Techniques and parameterization of the RRFS version 1.0 will be applied during the development MPAS version RRFS 2.0.

More info here.

The MPAS uses a honeycomb geometry that can be compressed or stretched for greater detail in active weather regions.

Expandable- compressible geometry can the solution of the current RRFS version 1 difficulties.

Posted Sunday 12/17 @ 10:13 AM — The latest RRFS development page now has the model being operational in early 2025 instead of Fall 2024. Current version is 0.7.7. Updates here.

Posted November 18, 2023

NOAA has been developing a new model, the RRFS (“Rapid Refresh Forecast System“) which will be the beginning of a major advance in high resolution weather forecasting. The model will run hourly forecasts to 18 hours, will have a high (3 km) resolution, and its 00z, 06z, 12z, and 18z forecasts will extend out to 60 hours. It will also have an statistical ensemble component version and a “smoke” forecast version.

Its development was begun in 2016-2017 and early experimental versions have been posted online starting 2021.

The RRFS takes much of its physics from the HRRR and will use the advanced FV3 core used in the recently updated GFS.

The RRFS is going through a series of continued experimentation, testing and fine tuning and the groundwork is being laid for it to be operational sometime around September 2024.

Some of the current ongoing development information is being logged here. When released, it will be RRFS version 1.0, but as of this posting (Nov 2023) , it’s only at version 0.7.3 and is being referred to as “RRFS-A“.

About 6 months after it is released, many of the models I look at regularly ( the HRRR, NAM, NAM-NEST, RAP, SREF, and all three flavors of the HIRESW) will cease operation.

My long-standing mantra when it comes to snowstorms, “Never Ignore the NAM”, will become a relic of the past.

I’ve always felt there are “too many models” and it appears that the RRFS is incorporating and building on all of the best approaches to numerical weather modeling that have been learned from these earlier models.

NOAA/NWS has been making the development version and their testbed variants available on a NOAA- Amazon Web Services site (AWS) for since 2021.

In recent weeks, I’ve been experimenting with downloading these RRFS runs. The experimental version is hosted on Amazon Web Services (AWS) NOAA-Open Data and has certain constraints that the main NOAA NOMADS site doesn’t have, along with different directory structures (buckets). Nonetheless, I hope to be downloading and using the RRFS model in some forecasts soon.

The release of RRFS version 1 will truly be a big deal.

For those of you that wish to explore more, here are some excellent web links related to the RRFS—







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