Controls of Discrete Convective Updrafts in Quasi-Linear Convective Systems and their Impact on Tornadogenesis

Updraft structure within quasi-linear convective systems (QLCSs) is generally characterized as slabular, though lifting can become more discrete several kilometers above the surface. It is hypothesized that locations of relatively deep, discrete updraft cores can indicate regions of enhanced vorticity stretching and thus increased tornado potential. To address this hypothesis, a tornadic QLCS dataset is developed using gridded multi-radar multi-sensor (MRMS) data and objective identification of storm mode from radar-identified storms associated with every tornado track from 2021-2023. Of the 3296 tornado tracks analyzed, 792, or approximately 24%, were associated with a QLCS, slightly higher than past studies of storm mode. Within identified QLCSs, upper tropospheric MRMS data are used to locate elevated reflectivity cores, an updraft proxy, for each tornado event. The area and maximum reflectivity value of each core are recorded. Over 93% of QLCS tornadoes analyzed are co-located with reflectivity cores, where co-location is defined as a core within 25 km of a tornado’s starting location at the time of tornadogenesis. 100% of tornadoes rated EF-2 or higher are co-located with elevated reflectivity values. Trends in reflectivity core characteristics, such as area, and tornado characteristics, such as path length, are also explored. An analysis of environmental data associated with each tornado indicates wind shear and equilibrium level height may control the occurrence of reflectivity cores more directly than CAPE. Results show that updraft proxies such as MRMS reflectivity cores may be useful in identifying locations of greatest tornado potential within QLCSs, helping improve tornado warning lead times.