Airflow Configurations of Warm Season Southerly Low-Level Wind Maxima in the Great Plains. Part I: Spatial and Temporal Characteristics and Relationship to Convection

Abstract

Abstract A synoptic climatological approach was used to investigate 1) the airflow characteristics of southerly low-level wind maxima in the Great Plains, 2) the typical thermodynamic environments in which low-level wind maxima form, 3) the convergence fields accompanying the wind maxima, and 4) the associated patterns of cloud-to-ground lightning activity. A total of 260 low-level jet events that occurred at either 0000 or 1200 UTC during the warm seasons (Apr–Sep) of 1991–92 were employed in the analysis. The spatial configuration of southerly low-level jets was shown to be considerably more complex than previously portrayed. A subjective classification of the jet events—based on streamline curvature, latitudinal extent, and the orientation of confluence and deformation zones—resulted in 12 distinct configuration types. Only 37% of the events were broadly classified as anticyclonically curving jets, even though the majority of previous case studies focused on this type of wind maximum. Another unanticip...