The development of a new observational system called LISDAD (Lightning Imaging 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 flashes/rain, with some values reaching 500 flashes/min. Similar to earlier results for thunderstorm microbursts, the peak flash rate precedes the severe weather at the ground by 5-20 minutes. A distinguishing feature of severe storms is the presence of lightning "jumps"-abrupt increases in flash 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 severe weather at the surface and simultaneously stimulates the ice microphysics that drives the intracloud lightning activity.

Abstract. Radiation with frequencies of 5-30 Hz is ducted between Earth's surface and ionosphere with little attenuation; at the lowest frequencies, waves travel several times around the Earth before losing most of their energy. Much of this radiation is produced by lightning. Here we assume that all of this radiation is produced by lightning, and attempt to invert the observed electric and magnetic fields to infer the global lightning activity. We show 10 days of inversions. For these 10 days, the inferred average rate of vertical charge transfer squared is only 1.7 10 s (C km)2/s. Other studies suggest that the root mean square moment change of a flash is about 166 Coulomb kilometers. If we naively assume that each of these flashes is composed of four equally sized strokes, then we conclude that our entire observed signal could be produced by only 22 flashes per second.

This forecaster’s note documents the early history (1989–1998) of the use of total lightning data within an operational forecast and warning environment. As early as 1989, the Melbourne field office of the National Weather Service had access to real-time cloud-to-ground lightning data. In 1993, the Lightning Detection and Ranging system (capable of detecting all types of lightning flashes) became available. In 1996, these two lightning data sets, along with radar data, were incorporated into the Lightning Imaging Sensor Data Applications Display (LISDAD) system. During a 3-y period (1996–1998 inclusive), the LISDAD permitted forecasters to observe relationships of total lightning with a variety of convective events, including pulse-severe thunderstorms in the warm season, cool-season tornadic supercells, tornadic mini-supercells in tropical cyclones, and non-severe storms. Major findings included: 1) “lightning jumps” with warm-season pulse-severe storms several minutes prior to reported severe weather; 2) cool-season tornadic supercell storms with very large total flash rates; and 3) tornadic mini-supercells in tropical cyclones produced only small amounts of lightning, however this sporadic activity benefited forecasters by implying stronger updraft development in a favorably sheared environment, in turn implying possible storm rotation and potential tornadogenesis. Finally, given the availability of total lightning datasets to operational forecasters, local forecast products could more effectively provide the public information about the overall lightning threat.