A Comparison between Tornadic and Nontornadic QLCS Mesovortices Using a Multiradar Analysis of Operational and Experimental MRMS Products

Abstract Quasilinear convective system (QLCS) tornadoes have become an active area of research in recent years. Generally weaker, shorter lived, rapidly developing, and with shallower rotation than supercell tornadoes, they present a considerable challenge to forecast and warning operations. This study tracks 121 tornadic and 153 nontornadic (null) QLCS mesovortices spanning across numerous regions of the CONUS in an effort to understand evolutionary differences in mesovortex behavior leading up to a successful or failed mode of tornadogenesis via the Multi-Radar Multi-Sensor (MRMS) system in a multiradar framework. The multiradar framework allows for a comprehensive three-dimensional analysis able to capture storm-scale characteristics both near the surface and aloft. Vertical profiles of azimuthal shear, divergent shear, and dual-polarization moments are retained along the path of each mesovortex. Tornadic mesovortices are nearly 1 km deeper in the median and often exhibit stronger cyclonic rotation compared to nulls approximately 20 min prior to tornadogenesis, a signal consistent with prior observational studies. Moreover, tornadic mesovortices tend to exhibit higher magnitudes of divergence at the near surface through 6 km above ground level (AGL) and deeper convergence extending through 4 km AGL approximately 20 min prior to tornadogenesis. Tornadic events often display higher specific differential phase K DP , while differential reflectivity Z DR is highly variable across regions of the CONUS. Environmental 0–3 km AGL storm relative helicity is higher in tornadic events 1 h prior to tornadogenesis. Close-proximity (≤75-km range) mesovortices demonstrate higher variability than those in far proximity from the nearest radar. Significance Statement Quasilinear convective system (QLCS) tornadoes are usually weaker and shorter lived relative to supercell tornadoes making it difficult to anticipate tornadogenesis within these systems and provide ample lead times to save both life and property. This study used a merging of the Next Generation Weather Radar (NEXRAD) data to analyze mesovortices occurring along the leading edge of QLCSs. It was found that tornadic mesovortices often exhibit stronger and deeper counterclockwise rotation and showed stronger divergence from the near surface through 6 km in height 20 min before the tornado. However, other Doppler radar products, such as differential reflectivity, were shown to be highly variable across regions of the United States, yet specific differential phase was higher in the tornadic cases. Therefore, signs of tornadic potential can be shown for the QLCS mesovortices in our dataset when using dual-polarized radar data along with MRMS products.