A Case Study of Kinematical, Microphysical, and Lightning Characteristics of a Tornadic Supercell

The variability of the supercooled liquid water content (SCLW) within a storm is believed to be partly a function of storm’s updraft speeds. Thus, the storm dynamics control the SCLW, which in turn controls the charge structure of the storm. Recent research has also established that the differential reflectivity column height, measured by a polarimetric radar, can serve as an indicator of updraft strength. We aim to use high temporal resolution polarimetric radar data in combination with lightning mapping array data to investigate the fundamental relations between the kinematical, microphysical, and lightning properties of a tornadic supercell.

On 19 May 2013, the University of Oklahoma (OU) Advanced Radar Research Center’s mobile Rapid-scan, X-band, Polarimetric (RaXPol) radar scanned a tornado near Shawnee, Oklahoma which had a varying intensity throughout its lifecycle. At its most severe, the tornado produced EF-4 category winds. The radar was deployed three times, scanning the tornadic storm in PPI scan mode from a lowest tilt of 1° to 19° at an interval step of 2°, producing volume scans approximately every 40 s.

These radar observations are analyzed in conjunction with observations from the Oklahoma Lightning Mapping Array (OKLMA). The OKLMA detects lightning flash locations in three dimensions based on the time-of-arrival differences of very high frequency (VHF) emissions from discontinuous breakdown of lightning channels. Using source density plots from LMA data as a reference for charge structure of a storm, the SCLW can be estimated. Microphysical properties will be estimated using hydrometeor classification algorithms to classify the distribution and evolution of hydrometeors, while the LMA data will provide details like charge structure, flash locations, flash rate, and flash energy associated with the storm.