Many of the graphics in the ENSO blog are hybrids, with the data processing done in a scientific programming language (or sometimes in ArcGIS) and then polish provided by the Climate.gov graphics team using Adobe creative suite products. Michelle made a rough draft version of this animation to show us what she wanted, and then she handed over eps frames, which our graphics team turned into an animated gif using Adobe Photoshop. Not sure what she originally used to produce her rought draft. Perhaps she will weigh in...