DIAGNOSTIC STUDY OF A TROPICAL DISTURBANCE

Abstract

An area of disturbed weather over the Bahamas is studied in detail for the 3-day period, Aug. 9?11, 1966. The coupling of an upper level cold-core cyclone with an approaching low-level wave was largely responsible for the considerable increase in cloudiness and weather observed on August 9 and 10. Warm anomalies in the lower stratosphere were even larger than the cold anomalies of the upper troposphere, strongly suggesting the existence of large-scale vertical motions at both levels. Results from a diagnostic numerical model show that the Laplacian of thermal advection was the single most important forcing function contributing to tropospheric vertical motion. Agreement between observed cloudiness and calculated vertical motion was generally good.