Lightning Activity within a Tornadic Thunderstorm Observed by the Optical Transient Detector (OTD)

The first storm-scale, total lightning observations during tornadogenesis from space are presented. The NASA (National Aeronautics and Space Administration) OTD (Optical Transient Detector) overpass of an Oklahoma supercell, just minutes prior to tornado touchdown on 17 April 1995, detected a lightning flash rate of 45 flashes/ min. The total lighting activity was at least 15 times greater than the cloud-to-ground lightning activity detected by the National Lightning Detection Network (NLDN), indicating most of the lightning was intracloud. Total lightning rates were decreasing rapidly prior to tornadic touchdown. These observations are consistent with the limited results from recent ground based measurements of total lightning activity in tornadic storms, suggesting significant intracloud lightning and rapidly decreasing flash rates prior to tornado touchdown.