Case studies of tornadic storms have shown the importance of various sub-storm scale structures, including in updrafts/downdrafts and associated convergence/divergence regions in tornadogenesis and intensification. But, the existence of the features alone is not sufficient for tornadogenesis. The Doppler on Wheels (DOW) radars have collected dual-Doppler data in about 20 supercell storms, some tornadic, some non-tornadic, which allows for the characterization of these features using fine-scale resolution vector wind fields permitting structures, convergence/divergence, and vorticity to be diagnosed. Moreover, approximately 10 of these dual-Doppler cases also have in situ instrumentation, which allows for characterization of the air masses surrounding tornadoes. As part of the BEST (Boundary-layer Evolution and Structure of Tornadoes) project, during the 2024 tornado season, the DOWs collected an exemplary dual-Doppler data set near Duke, OK on May 23, 2024. Seven-second dual-Doppler data and a 4.2 km baseline allowed for the temporal and spatial resolution of quickly evolving small-scale features associated with vertical velocity production. The role of convergence boundaries in vertical vorticity production are identified as a tornado maintenance mechanism, and as these boundaries weaken and detach/move away from the tornado, dissipation occurs. Ongoing inter-comparison efforts between the ~20 dual-Doppler cases at different stages of tornado evolution and exemplary case studies like Duke, OK, will be presented, and commonalities that contribute to tornado evolution will be discussed.
Kosiba et al. (Fri,) studied this question.