Earlier this year I visited the European Center for Medium-Range Weather Forecasts, a European organization that produces global weather forecasts and performs research on how to improve those. The episode has three parts. First, Hilda Carr gives us an overview of the organization, its purpose and its history. Then I talk with Peter Bauer about weather and climate modeling and about encoding these models efficiently in software programs that run on supercomputers. Part three is a conversation with Tony McNally about where the ECMWF gets its data and how it is continuously fed into the “running” model.