9301288 Straus Determining the roles played by synoptic and planetary scale motions in maintaining large-scale atmospheric regimes and in causing transitions between distinct regimes is critically important in understanding low frequency atmospheric variability and is particularly germane to extended range (several weeks in advance) forecasting. Current medium range weather forecasting models are poor at predicting these transitions, hence, major changes in weather patterns are not well-forecast. Dr. Straus will use an atmospheric general circulation model (GCM) to conduct numerical forecasts designed to isolate the various components of the atmospheric circulation and the interaction among the various scales of motion. In this study, he also will attempt to separate midlatitude and tropical effects. The results of this research have a clear potential for improving extended range forecasting. ***
