Doppler Radar and Lightning Network Observations of a Severe Outbreak of Tropical
Cyclone Tornadoes

EUGENE W. MCCAUL JR.
Universities Space Research Association, Huntsville, Alabama
DENNIS E. BUECHLER
University of Alabama in Huntsville, Huntsville, Alabama
STEVEN J. GOODMAN
NASA Marshall Space Flight Center, Huntsville, Alabama
MICHAEL CAMMARATA
National Weather Service, Columbia, South Carolina
(Manuscript received 7 August 2003, in final form 15 December 2003)

ABSTRACT

Data from a singleWeather Surveillance Radar-1988 Doppler (WSR-88D) and the National Lightning Detection
Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak,
including three tornadoes that reached F3 intensity, within Tropical Storm Beryl’s remnants on 16 August 1994.
Comparison of the radar data with reports of tornadoes suggests that only 13 cells produced the 29 tornadoes
that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes,
and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for
11 h, spawning tornadoes over a time period spanning approximately 6.5 h. Several other tornadic cells also
exhibited great longevity, with cell lifetimes longer than ever previously documented in a landfalling tropical
cyclone (TC) tornado event. This event is easily the most intense TC tornado outbreak yet documented with
WSR-88Ds.

Time–height analyses of the three strongest tornadic supercells are presented in order to document storm
kinematic structure and to show how these storms appear at different ranges from a WSR-88D. In addition,
cloud-to-ground (CG) lightning data are examined in Beryl’s remnants. Although the tornadic cells were responsible
for most of Beryl’s CG lightning, their flash rates were only weak to moderate, and in all the tornadic
storms the lightning flashes were almost entirely negative in polarity. A few of the single-tornado storms produced
no detectable CG lightning at all. There is evidence that CG lightning rates decreased during the tornadoes,
compared to 30-min periods before the tornadoes. A number of the storms spawned tornadoes just after producing
their final CG lightning flashes. Contrary to the findings for flash rates, both peak currents and positive flash
percentages were larger in Beryl’s nontornadic storms than in the tornadic ones.