The Met Office say it will provide more accurate weather forecasting and a better understanding of climate change.
The UK government said in February 2020 it would invest $1.6 billion in the project. It is expected to be one of the top 25 supercomputers globally when it is up and running in the summer of 2022.
Vole plans to update it over the next decade as computing improves.
Stanford University assistant professor Morgan O'Neill, who is not involved in the project, said that it is an impressive public investment in the basic and applied sciences of weather and climate.
"Such a major investment in a state-of-the-art weather and climate prediction system by the UK is great news globally, and I look forward to the scientific advances that will follow."
The Met Office said the technology would increase their understanding of the weather and allow people to better plan activities, prepare for inclement weather, and get a better experience of climate change.