The Formation and Climatological Distribution of Tornadoes within Quasi-Linear Convective Systems

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Approximately 1000 tornadoes are observed within the U.S. annually. These tornadoes are spawned from a variety of parent storm types, including supercell thunderstorms and quasi-linear convective systems (QLCSs) such as squall lines and bow echoes.The horizontal extent of viable tornado-breeding sites is an order of magnitude larger in QLCSs than in individual supercells. QLCS tornadoes can be strong and produce extensive damage. Also, QLCS tornadogenesis appears to occur, on average, more rapidly than does supercell tornadogenesis from the perspective of Doppler radar. The geographical, seasonal, and diurnal distributions of QLCS tornadoes are unknown.A significant amount of research effort has been devoted to the study of supercell tornadogenesis, but no published research addresses specifically QLCS tornadogenesis. Owing to the related lack of fundamental knowledge of QLCS tornadogenesis/tornado climatology, it may be argued that operational meteorologists are generally unable to assess the potential risk of tornadic winds in QLCSs and, hence, properly alert the public to this danger. The Principal Investigator will undertake a complementary two-part study. The objectives are to: 1. Estimate the climatological distributions of QLCS-spawned tornadoes; characterize the environmental conditions under which they occur; determine radar-based attributes of tornadic versus non-tornadic QLCS.2. Gain an understanding of tornadic versus non-tornadic QLCS morphology and evolution.Successful completion of this research will increase fundamental knowledge of QLCS tornadoes and will have applications in severe weather forecasting and warning operations.