High-Resolution Dual-Doppler Analyses of the 29 May 2001 Kress, Texas, Cyclic Supercell

Abstract

On 29 May 2001, Doppler on Wheels radars collected data on a supercell near Kress, Texas. The supercellular storm, cyclic in nature, produced multiple mesocyclones throughout its lifetime. Dual-Doppler syntheses were conducted using a grid spacing of 100 m, resulting in the highest-resolution observational analysis of a cyclic supercell to date. In addition, collection of data from ground-based radar allowed for the analysis of near-ground features irresolvable with airborne radar, providing another advantage over previous studies. The syntheses revealed a number of evolving low-level mesocyclones over the observation period of 900 s. While nontornadic during the synthesis period, the supercell exhibited evidence of strong (vertical vorticity greater than 10?2 s?1) low-level circulation with classic cyclic structure and multiple tornadoes beginning 3600 s later. A comparison between the current results, conceptual models, and previous lower-resolution analyses is presented. A striking similarity exists between the cyclic evolution of the Kress storm during the synthesis time period and other previous cyclic conceptual models. However, differences did exist between the Kress storm and previously studied tornadic storms. Analysis showed that the rear-flank downdraft provided the only surface boundary associated with low-level mesocyclogenesis. Other characteristics, including forward-flank gust front structure and the orientation of low-level horizontal vorticity, also differed. In addition, there was a general lack of surface convergence associated with the forward-flank reflectivity gradient, yet convergence associated with the forward-flank gust front increased with height. Finally, a large component of crosswise horizontal vorticity was found to exist throughout the supercell environment, within both the inflow and outflow. Incorporating these differences, an attempt was made to identify possible mechanisms responsible for the lack of tornadogenesis during the synthesis time period.