The Unified Forecast System (UFS) Weather Model (WM) is a prognostic model that can be used for short- and medium-range research and operational forecasts. It can be run as an atmosphere-only model or as an atmospheric model coupled with one or more additional components, such as a wave or ocean model.

The UFS WM is constantly evolving, and new features are added at a rapid pace. Users can find those features in the develop branch, but documentation may be behind the latest updates. The UFS WM is tagged frequently for public and operational releases. The ufs-srw-v2.2.0 tag of the WM is the most recent public release of the UFS WM, which was released as part of the UFS Short-Range Weather (SRW) Application v2.2.0. This tag represents a snapshot of a continuously evolving system undergoing open development. Key architectural elements of the UFS Weather Model include:

• The Finite-Volume Cubed-Sphere (FV3) dynamical core is the computational part of an atmospheric model that solves the equations of fluid motion.
• The Flexible Modeling System (FMS) is a software framework for supporting the efficient development, construction, execution, and scientific interpretation of atmospheric, oceanic, and climate system models. It is used for functions such as parallelization. 
• The Common-Community Physics Package (CCPP) provides a framework and library of physics schemes that support interoperable atmospheric physics. Atmospheric physics is a set of numerical methods approximating the effects of small-scale processes such as clouds, turbulence, radiation, and their interactions. 
• Stochastic Physics schemes apply randomized perturbations to the physical tendencies, or physical parameters, of a model in order to compensate for model uncertainty. 

The Weather Model is currently used in NOAA’s operational Global Forecast System (GFS). Additionally, the UFS Short-Range Weather (SRW) Application uses the Weather Model in its v2.2.0 release (October 2023), and the UFS Medium-Range Weather (MRW) Application can run the WM in coupled or atmosphere-only mode. 

The UFS WM code is portable and can be used with Linux and Mac operating systems and with Intel and GNU compilers. It has been tested on a variety of platforms widely used by atmospheric scientists, including NOAA’s Hera system, the National Center for Atmospheric Research (NCAR) Derecho system, and the Mississippi State University (MSU)/NOAA Orion system.

Those wishing to contribute to the development of the UFS WM should become familiar with the procedures for running the model as a standalone component and for executing the regression tests described in the UFS WM GitHub wiki to make sure that no inadvertent changes to the results have been introduced during the development process.

Support for the UFS WM is provided through the UFS WM Discussions Forum by the Developmental Testbed Center (DTC) and other groups involved in UFS development, including NOAA’s Environmental Modeling Center (EMC), NOAA research laboratories (GFDL, NSSL, ESRL, and AOML), the Earth Prediction Innovation Center (EPIC), and NCAR. UFS users and developers are encouraged not only to post questions but also to help address questions posted by other members of the community. More information about the UFS Community can be found on the UFS Community Portal. 

Links:

Evaluating Computational Performance in Weather Model Testing

UFS WM GitHub repository

UFS WM README.md file

UFS WM “develop” branch User’s Guide

Some supported configurations of the WM are documented in the Configurations chapter. The full list of tested configurations is listed in the WM’s rt.conf file, which contains all regression tests (RTs). 

The User’s Guide includes information on building and running the WM, including the use of RT scripts. 

The WM wiki contains developer information, including information on supported platforms, regression testing policies & procedures, and tutorials

General UFS Information:

• The UFS Wiki is the central community page for Unified Forecast System (UFS) software. It contains information on UFS policies, applications, and supported platforms.
• The Unified Workflow (UW) tools outline contains information on standalone tools for overcoming common technical challenges encountered when running numerical weather prediction workflows.
• The Debugging Guide is a general guide to debugging Earth System Modeling software.