Characteristics of cloud-to-ground lightning associated with violent tornado-producing supercells

Abstract

Cloud-to-ground (CG) lightning patterns were analyzed to identify relationships to tomadogenesis in 42 different violent-tornado producing supercells that occurred between January 1989 and November 1992. A relationship between five-minute CG flash rate tendencies and tornado formation appeared in two different patterns. Thirty-one of the storms were characterized by a peak in CG flash rate and a subsequent decrease until tornado formation (TYPE 1); twenty-two storms were characterized by a decrease in CG activity coincident with tornado touchdown (TYPE II). Storms exhibiting significant positive polarity were generally associated with long-track tornadoes, F-5 damage ratings or outbreak conditions. Overall CG flash rate, however, appeared to have little correlation with tomadogenesis (CG flash rate ranged from 0.18-46 min-). CG flash patterns may be indicative of different storm processes, but it may be necessary to detect intracloud flashes simultaneously to fully characterize the electrical/dynamical relationships in a thunderstorm.