The behavior of total lightning activity in severe Florida thunderstorms

The development of a new observational system called LISDAD (Lightning Imag ing Sensor Demonstration and Display) has enabled a study of severe weather in central Florida. The total flash rates for storms verified to be severe are found to exceed 60 fpm, with some values reaching 500 fpm. Similar to earlier results for thunderstorm microbursts, the peak flash rate precedes the severe weather at the ground by 5-20 min. A distinguishing feature of s evere storms is the presence of lightning 'jumps' - abrupt increases in fla sh rate in advance of the maximum rate for the storm. The systematic total lightning precursor to severe weather of all kinds - wind, hail, tornadoes - is interpreted in terms of the updraft that sows the seeds aloft for seve re weather at the surface and simultaneously stimulates the ice microphysic s that drives the intracloud lightning activity. (C) 1999 Elsevier Science B.V. All rights reserved.