Cheyenne is a nice basement system. Only needs 1.75 MW. The system which replaced Cheyenne is Derecho, a 19.8 petaflop system.
https://news.ucar.edu/132904/scientists-nationwide-launch-first-projects-new-ncar-supercomputer Last fall, NOAA/NWS replaced theirs (one in Manassas, one in Phoenix) with new 12.5 petaflop systems. As the models evolve, they get more demanding. They were able to implement new and enhanced forecast models on the new machines. https://www.noaa.gov/news-release/noaa-completes-upgrade-to-weather-and-climate-supercomputer-system De
