RELATION OF LONG-PERIOD CIRCULATION ANOMALIES TO TROPICAL STORM FORMATION AND MOTION

Abstract

Tropical-cyclone frequency in the entire North Atlantic and in the preferred sites of tropical cyclogenesis in the Atlantic undergo fluctuations which composite charts show to be related to the form and position of the planetary waves. Long-period conditions propitious for tropical storm formation in particular areas of the Atlantic show some rather well-defined circulation patterns which are not alike for all areas. These varying circulation patterns are also shown to form the framework for steering tropical cyclones after their generation. It is concluded feasible to use the various composite charts as guides in the preparation of long-range forecasts of hurricane formation and motion.