Storm-environment interactions controlling the probability of supercell tornadogenesis

Funding source: National Science Foundation

Duration: 2021-2025

Recent research has specifically connected the lower tropospheric wind profile (specifically, near-ground storm-relative helicity; “SRH”) to the dynamical accelerations that support stretching of near-surface vorticity into a tornado.  But, our community has yet to explain why tornadogenesis so frequently fails to occur within seemingly favorable environments.  We require more detailed explanations of the tornadogenesis process, including the failure points that hinder tornadogenesis in nontornadic supercells, and their physical linkages to specific environmental traits. The goals of the proposed research are to: 1) explain how environmental heterogeneity modulates tornado production in supercells; 2) establish the relative importance of environmental vs. storm generated SRH in the dynamic lifting produced by low-level mesocyclones; and, 3) explain the origins of large environmental SRH.    

Collaborative Research: Propagation, Evolution and Rotation in Linear Storms (PERiLS)

Funding source: National Science Foundation

Duration: 2021-2025

Quasi-linear convective systems (QLCSs) are responsible for approximately a quarter of all tornado events in the U.S. The majority of QLCS tornadoes occur in the Southeastern (SE) U.S. and the  percentage of tornadoes associated with QLCSs, as opposed to supercells, appears to be higher in this  region than in the remainder of the U.S. Unfortunately, common forecast skill metrics are significantly worse in QLCS tornado events than in supercell tornado events. This is due, in part, to our lack of understanding regarding QLCS tornadogenesis processes and is compounded by short temporal and small spatial scales for QLCS tornadogenesis, which are not often captured by the conventional operational radar network. PERiLS (Propagation, Evolution and Rotation in Linear Storms) is a field project (slated for Spring 2022 and Spring 2023) that will combine critical instruments from NSF and NOAA to provide the sampling necessary to address environmental factors and storm processes that lead to QLCS tornadogenesis.