On the Apparent Relationship between Convective Activity and the Shape of 500 mb Troughs

Abstract

A study was made of the surface occurrence of convective activity during the late spring and summer months for an eight-year period over a region of the central United States. It was found that there was a significant increase in the amount of convective activity as measured by thunderstorm when 500 mb troughs with a northwest to southeast (negative) tilt were present in the area. The enhanced convection was significantly greater than that activity associated with the presence of 500 mb troughs with a more ordinary tilt (or shape). An extension of the study to the winter mouths over a two-year period showed a similar but not so striking association between convective activity and negatively tilted troughs. The observations offer some support for a theoretical argument that convection nay be associated with an equatorward flux of relative angular momentum.