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Clark D. Payne, Terry J. Schuur, Donald R. MacGorman, Michael I. Biggerstaff, Kristin M. Kuhlman, and W. David Rust

Abstract

On 30 May 2004, a supercell storm was sampled by a suite of instrumentation that had been deployed as part of the Thunderstorm Electrification and Lightning Experiment (TELEX). The instrumentation included the Oklahoma Lightning Mapping Array (OK-LMA), the National Severe Storms Laboratory S-band Weather Surveillance Radar-1988 Doppler (WSR-88D) polarimetric radar at Norman, Oklahoma, and two mobile C-band, Shared Mobile Atmospheric Research and Teaching Radars (SMART-R). Combined, datasets collected by these instruments provided a unique opportunity to investigate the possible relationships among the supercell’s kinematic, microphysical, and electrical characteristics. This study focuses on the evolution of a ring of lightning activity that formed near the main updraft at approximately 0012 UTC, matured near 0039 UTC, and collapsed near 0050 UTC. During this time period, an F2-intensity tornado occurred near the lightning-ring region. Lightning density contours computed over 1-km layers are overlaid on polarimetric and dual-Doppler data to assess the low- and midlevel kinematic and microphysical characteristics within the lightning-ring region. Results indicate that the lightning ring begins in the middle and upper levels of the precipitation-cascade region, which is characterized by inferred graupel. The second time period shows that the lightning source densities take on a horizontal u-shaped pattern that is collocated with midlevel differential reflectivity and correlation coefficient rings and with the strong cyclonic vertical vorticity noted in the dual-Doppler data. The final time period shows dissipation of the u-shaped pattern and the polarimetric signatures as well as an increase in the lightning activity at the lower levels associated with the development of the rear-flank downdraft (RFD) and the envelopment of the vertical vorticity maximum by the RFD.

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Donald R. MacGorman, W. David Rust, Terry J. Schuur, Michael I. Biggerstaff, Jerry M. Straka, Conrad L. Ziegler, Edward R. Mansell, Eric C. Bruning, Kristin M. Kuhlman, Nicole R. Lund, Nicholas S. Biermann, Clark Payne, Larry D. Carey, Paul R. Krehbiel, William Rison, Kenneth B. Eack, and William H. Beasley

The field program of the Thunderstorm Electrification and Lightning Experiment (TELEX) took place in central Oklahoma, May–June 2003 and 2004. It aimed to improve understanding of the interrelationships among microphysics, kinematics, electrification, and lightning in a broad spectrum of storms, particularly squall lines and storms whose electrical structure is inverted from the usual vertical polarity. The field program was built around two permanent facilities: the KOUN polarimetric radar and the Oklahoma Lightning Mapping Array. In addition, balloon-borne electric-field meters and radiosondes were launched together from a mobile laboratory to measure electric fields, winds, and standard thermodynamic parameters inside storms. In 2004, two mobile C-band Doppler radars provided high-resolution coordinated volume scans, and another mobile facility provided the environmental soundings required for modeling studies. Data were obtained from 22 storm episodes, including several small isolated thunderstorms, mesoscale convective systems, and supercell storms. Examples are presented from three storms. A heavy-precipitation supercell storm on 29 May 2004 produced greater than three flashes per second for 1.5 h. Holes in the lightning density formed and dissipated sequentially in the very strong updraft and bounded weak echo region of the mesocyclone. In a small squall line on 19 June 2004, most lightning flashes in the stratiform region were initiated in or near strong updrafts in the convective line and involved positive charge in the upper part of the radar bright band. In a small thunderstorm on 29 June 2004, lightning activity began as polarimetric signatures of graupel first appeared near lightning initiation regions.

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