Evolution of Cloud-to-Ground Lightning Discharges in Tornadic Thunderstorms

摘要

Air Force operations are directly impacted by weather on a daily basis. Erroneous forecasts negatively impact mission readiness and consequently cost the government time, in terms of wasted man-hours, and money. Advanced forecast lead-time could make a difference to minimize loss to both USAF personnel and assets. This study examined lightning data from 64 storm events from 1995-2000 in search of unique lightning signatures indicative of tornadic activity. Overall flash rates, percentage of positive flashes, positive and negative peak currents and multiplicity for each case were separated into two categories based on tornado intensity and season of occurrence. Based on the research results, there is little evidence to support the theory that specific lightning trends emerge prior to tornadogenesis. Due to the inconsistent and unreliable nature of the results, exclusive use of this time-series technique is not recommended for use in operational forecasting. The use of conventional methods, such as radar and/or satellite, used in conjunction with cloud-to- ground lightning flash data may, however, provide insight as to how electrical and physical changes relate to the development of tornadoes within a storm. Intracloud lightning may also provide additional information on tornado development and should be included in future research projects.