HPSF Conference 2025

Numerical weather prediction (NWP) systems are complex, coupled models with several distinct components. They are often developed by different organizations: national agencies, research institutes, universities, and the community. Naturally, they require extensive third-party libraries and run on a wide range of computational platforms, from the largest high-performance computing systems (HPCs) to low-spec GitHub action runners.

To address this challenge of ever-increasing complexity, in 2021 the Joint Center for Satellite Data Assimilation (JCSDA) and NOAA’s Environmental Modeling Center (EMC) created spack-stack, a novel, collaborative effort geared towards universal and portable NWP software environments based on the spack package manager for supercomputers developed at LLNL. The spack-stack collaboration has grown since its inception, and as of 2025 includes the United States Naval Research Lab (NRL) and NOAA’s Earth System Prediction Center (EPIC). The spack-stack software environments are also increasingly used at NASA’s Global Modeling and Assimilation Office (GMAO), making it a core component of some of the Nation’s flagship NWP systems.