Although tornadoes produced by quasi-linear convective systems (QLCSs) generally are weak and short-lived, they have high societal impact due to their proclivity to develop over short time scales, within the cool season, and during nighttime hours. Precisely why they are weak and short lived is not well understood, thus motivating the recently published study by Geoff Marion and Jeff Trapp.
A strong correlation between low-level mesocyclone width and TLV intensity is identified, with a weaker correlation in the low-level updraft intensity. The tilt and depth of the updraft are found to have little correlation to tornado intensity. Comparing QLCS and isolated supercell updrafts within these simulations, the QLCS updrafts are less persistent, with the standard deviations of low-level vertical velocity and updraft helicity to be approximately 48% and 117% greater, respectively. A forcing decomposition reveals that the QLCS cold pool plays a direct role in the development of the low-level updraft, providing the benefit of additional forcing for ascent while also having potentially deleterious effects on both the low-level updraft and near-surface rotation. The negative impact of the cold pool ultimately serves to limit the persistence of rotating updraft cores within the QLCS.
This article was published in the AMS Journal of Atmospheric Sciences. To see the rest of this article, please visit https://doi.org/10.1175/JAS-D-20-0164.1.