2026-09-23T15:07:41Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/115775 2023-07-11 col_2142_5131 col_2142_14839 com_2142_5130 com_2142_14838 com_2142_13459 com_2142_8903

Trapp, Robert J Kosiba, Karen Klees, Alicia 2022-05 application/pdf en text Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms The student, James Goodnight, accepted the attached license on 2022-04-25 at 11:56. The student, James Goodnight, submitted this Thesis for approval on 2022-04-25 at 12:08. This Thesis was approved for publication on 2022-04-26 at 11:59. DSpace SAF Submission Ingestion Package generated from Vireo submission #17755 on 2022-11-11 at 17:38:03 Quantification of QLCS tornadogenesis, associated characteristics, and environments across a large sample Goodnight, James Seth 2022-04-26 QLCS tornadogenesis The skillful prediction of tornadoes produced by quasi-linear convective systems (QLCSs) is a well-known operational forecasting challenge. This study was motivated by the possibility that the tornado warning potential depends on the generalized mechanism of QLCS tornadogenesis, namely, horizontal shearing instability and stretching (H&S) and tilting and stretching (T&S). Thus motivated, the manual identification of the tornadogenesis mechanism of 530 QLCS tornadoes was performed using heuristic yet process-driven criteria based on single Doppler radar (WSR-88D) data. This included 214/213/103 tornadoes that occurred during 2019/2017/2016, respectively. As a function of genesis mechanism, 36% appear to have formed via H&S, and 60% appear to have formed via T&S; the mechanism of the remaining 4% could not be determined, based on our methodology. It was found that approximately 30% of the H&S cases were operationally warned before tornadogenesis compared to 44% of the T&S cases. This is believed to be related to the attributes of the associated tornadic vortices: T&S produced vortices that were stronger and had a larger vertical extent than those produced through H&S. It was also found that T&S tornadoes were more common during the warm season and displayed a diurnal, midafternoon peak in frequency. A complementary effort to explore the environmental characteristics of QLCS tornadogenesis revealed that both mechanisms were supported in similar environments. The exception was pre-tornadic frontogenesis, which was more prominent for cool-season H&S cases, and suggestive of a more significant role of the larger-scale meteorological forcing in the vertical vorticity that fosters the H&S tornadogenesis. Thesis eng https://hdl.handle.net/2142/115775 This Work has been submitted to Weather and Forecasting. Copyright in this Work may be transferred without further notice. M.S. Thesis Atmospheric Sciences University of Illinois at Urbana-Champaign Atmospheric Sciences