The Influence of Carl—Gustaf Rossby on Mesoscale Weather Prediction and an Outlook for the Future

This article presents an overview of the advances in mesoscale prediction from the time of Rossby to the present and an outlook for the future. The first part traces the evolution of research and forecasting based upon the conservation of certain properties on isentropic coordinates. It begins with Rossby's use of these properties to identify and follow air masses and concludes with current use of the isentropic/potential vorticity framework to define air motions and to describe cyclones, fronts, and associated mesoscale precipitation systems, as well as numerical weather prediction in isentropic coordinates. Highlights of this historical research on mesoscale prediction are presented. Regarding future advances in mesoscale observations and prediction, the authors suggest that, for the next decade, the prospects for global mesoscale datasets are not encouraging: Researchers will have to be content with datasets with resolutions considerably below the resolution that is likely to be available from operational numerical weather prediction models. The exceptions will be confined to limited continental regions. In spite of this, useful forecasts of mesoscale phenomena out to several days should be possible in certain situations, not only in the limited regions where initial states can be defined at high resolution, but elsewhere, provided that the synoptic-scale systems can be initially well defined and, subsequently, well forecast.