Vertically-Pointing Radar Observations of Convective Updrafts and Downdrafts Associated with Cool-Season QLCSs over Northern Alabama

Quasi-linear convective systems (QLCSs) are a relatively common occurrence in northern Alabama during the cool-season months. Often these storms develop in high-shear, low-CAPE (HSLC) environments. QLCSs can produce an array of severe weather such as tornadoes, damaging straight-line winds, lightning, and heavy precipitation. The goal of this study is to characterize the kinematic and thermodynamic properties associated with twelve severe QLCS events using an array of meteorological instrumentation. Using the University of Alabama in Huntsville’s (UAH) high resolution vertically pointing X-band profiling radar (XPR) and the National Oceanic Atmospheric Administration’s (NOAA) S-band precipitation profiler at the Courtland Airport, the reflectivity, signal-to-noise ratio (SNR), depth, width, and magnitude of the updraft and downdrafts are analyzed. Preliminary results show that some of the QLCSs have a maximum updraft on the order of ~20 m s^-1 confined to the lowest three kilometers of the storm, while the maximum adjacent downdraft corresponds to the high reflectivity and SNR values at the lower levels due to precipitation offloading. In addition to these vertically pointing radars, a 915 MHz wind profiler, 449 MHz wind profiler, surface observations, balloon and model soundings, the C-band Advanced Radar for Meteorological Operational Research (ARMOR), and lightning data will be used to quantify the characteristics of the QLCSs. Surface observations indicate a reduction in temperature, θ_e, and θ_v during the passage of the QLCS. The reduction in θ_e and θ_v is used to assess the cold pool strength. In addition, a pressure increase (up to approximately 5 hPa for some cases) is also observed with the passage of the QLCS. The magnitude of the temperature reduction and pressure increase are utilized to identify the propagation mechanism (e.g., density current vs. bore). Understanding the kinematic and thermodynamic properties of QLCSs will provide vital information on the kinematics of updrafts and downdrafts, along with important insights into the potential differences between nontornadic and tornadic QLCSs.