{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/107983"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/107983","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"The observed relationship between tornado intensity and pretornadic mesocyclone characteristics and environments","abstract":"Trapp et al. (2017, JAS) used idealized model simulations of supercell thunderstorms to demonstrate support of their hypothesis that wide, intense tornadoes should form more readily out of wide, rotating updrafts. Observational data were used herein to test the generality of this hypothesis, especially to tornado-bearing convective morphologies such as quasi-linear convective systems (QLCSs), and within environments such as those found in the southeastern U.S. during boreal spring and autumn. A new radar dataset was assembled that focuses explicitly on the pre-tornadic characteristics of the mesocyclone, such as width and differential velocity: the pre-tornadic focus allows us to eliminate the effects of the tornado itself on the mesocyclone characteristics. GR2Analyst was used to manually analyze 80 tornadic events during the period 1 April 2011 to 1 May 2019. The corresponding tornadoes had damage (EF) ratings ranging from EF0 to EF5, and all were within 100 km of a WSR-88D. A key finding is that the linear regression between the mean, pre-tornadic mesocyclone width and the EF rating of the corresponding tornado yields a coefficient of determination (R2) value of 0.75. This linear relationship is the higher for discrete (supercell) cases (R2=0.82), and lower for QLCS cases (R2=0.37). Overall, we have found that pre-tornadic mesocyclone width tends to be a persistent, relatively time-invariant characteristic that is a good predictor of potential tornado intensity. In contrast, the pre-tornadic mesocyclone intensity (differential velocity) tends to exhibit considerable time variability, and thus would offer less reliability in anticipating tornado intensity. Additionally, the environmental characteristics of each case were analyzed and compared to the pre-tornadic mesocyclone characteristics to better understand the environmental controls on the pre-tornadic mesocyclone width and intensity. Initial findings support a stronger relationship between the pre-tornadic mesocyclone and thermodynamic parameters than with measures of vertical wind shear with a seasonal dependence.","abstract_html":"Trapp et al. (2017, JAS) used idealized model simulations of supercell thunderstorms to demonstrate support of their hypothesis that wide, intense tornadoes should form more readily out of wide, rotating updrafts. Observational data were used herein to test the generality of this hypothesis, especially to tornado-bearing convective morphologies such as quasi-linear convective systems (QLCSs), and within environments such as those found in the southeastern U.S. during boreal spring and autumn. A new radar dataset was assembled that focuses explicitly on the pre-tornadic characteristics of the mesocyclone, such as width and differential velocity: the pre-tornadic focus allows us to eliminate the effects of the tornado itself on the mesocyclone characteristics. GR2Analyst was used to manually analyze 80 tornadic events during the period 1 April 2011 to 1 May 2019. The corresponding tornadoes had damage (EF) ratings ranging from EF0 to EF5, and all were within 100 km of a WSR-88D. A key finding is that the linear regression between the mean, pre-tornadic mesocyclone width and the EF rating of the corresponding tornado yields a coefficient of determination (R2) value of 0.75. This linear relationship is the higher for discrete (supercell) cases (R2=0.82), and lower for QLCS cases (R2=0.37). Overall, we have found that pre-tornadic mesocyclone width tends to be a persistent, relatively time-invariant characteristic that is a good predictor of potential tornado intensity. In contrast, the pre-tornadic mesocyclone intensity (differential velocity) tends to exhibit considerable time variability, and thus would offer less reliability in anticipating tornado intensity. Additionally, the environmental characteristics of each case were analyzed and compared to the pre-tornadic mesocyclone characteristics to better understand the environmental controls on the pre-tornadic mesocyclone width and intensity. Initial findings support a stronger relationship between the pre-tornadic mesocyclone and thermodynamic parameters than with measures of vertical wind shear with a seasonal dependence.","abstract_has_math":false,"creators":["Sessa, Michael F"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Atmospheric Sciences","degree_department":null,"school":null,"contributors":["Trapp, Robert J"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-08-26T21:54:51Z","date_published":"2020-08-26T21:54:51Z","updated_at":"2026-07-22T22:24:47Z","subjects":["severe thunderstorms","tornadoes","mesocyclones"],"languages":["en"],"rights":["Copyright 2020 Michael Sessa"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/107983","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Trapp, Robert J"]},{"key":"dc:creator","label":"Author","values":["Sessa, Michael F"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-08-26T21:54:51Z","2020-05-05","2020-05"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Atmospheric Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["severe thunderstorms","tornadoes","mesocyclones"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Michael Sessa"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/107983"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Trapp et al. (2017, JAS) used idealized model simulations of supercell thunderstorms to demonstrate support of their hypothesis that wide, intense tornadoes should form more readily out of wide, rotating updrafts. Observational data were used herein to test the generality of this hypothesis, especially to tornado-bearing convective morphologies such as quasi-linear convective systems (QLCSs), and within environments such as those found in the southeastern U.S. during boreal spring and autumn. A new radar dataset was assembled that focuses explicitly on the pre-tornadic characteristics of the mesocyclone, such as width and differential velocity: the pre-tornadic focus allows us to eliminate the effects of the tornado itself on the mesocyclone characteristics. GR2Analyst was used to manually analyze 80 tornadic events during the period 1 April 2011 to 1 May 2019. The corresponding tornadoes had damage (EF) ratings ranging from EF0 to EF5, and all were within 100 km of a WSR-88D. A key finding is that the linear regression between the mean, pre-tornadic mesocyclone width and the EF rating of the corresponding tornado yields a coefficient of determination (R2) value of 0.75. This linear relationship is the higher for discrete (supercell) cases (R2=0.82), and lower for QLCS cases (R2=0.37). Overall, we have found that pre-tornadic mesocyclone width tends to be a persistent, relatively time-invariant characteristic that is a good predictor of potential tornado intensity. In contrast, the pre-tornadic mesocyclone intensity (differential velocity) tends to exhibit considerable time variability, and thus would offer less reliability in anticipating tornado intensity. Additionally, the environmental characteristics of each case were analyzed and compared to the pre-tornadic mesocyclone characteristics to better understand the environmental controls on the pre-tornadic mesocyclone width and intensity. Initial findings support a stronger relationship between the pre-tornadic mesocyclone and thermodynamic parameters than with measures of vertical wind shear with a seasonal dependence.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-08-25 without embargo terms","The student, Michael Sessa, accepted the attached license on 2020-05-04 at 14:46.","The student, Michael Sessa, submitted this Thesis for approval on 2020-05-04 at 15:13.","This Thesis was approved for publication on 2020-05-05 at 16:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15195 on 2020-08-25 at 17:11:53","Made available in DSpace on 2020-08-26T21:54:51Z (GMT). No. of bitstreams: 2 SESSA-THESIS-2020.pdf: 12523517 bytes, checksum: 626cd3390e9321db663a9fe867d312db (MD5) LICENSE.txt: 4210 bytes, checksum: 7499337eb2a1d1ed01eee3a62132a3cf (MD5) Previous issue date: 2020-05-05"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The observed relationship between tornado intensity and pretornadic mesocyclone characteristics and environments"]}]}],"canonical_facts":{"dc:contributor":["Trapp, Robert J"],"dc:creator":["Sessa, Michael F"],"dc:date":["2020-08-26T21:54:51Z","2020-05-05","2020-05"],"dc:description":["Trapp et al. (2017, JAS) used idealized model simulations of supercell thunderstorms to demonstrate support of their hypothesis that wide, intense tornadoes should form more readily out of wide, rotating updrafts. Observational data were used herein to test the generality of this hypothesis, especially to tornado-bearing convective morphologies such as quasi-linear convective systems (QLCSs), and within environments such as those found in the southeastern U.S. during boreal spring and autumn. A new radar dataset was assembled that focuses explicitly on the pre-tornadic characteristics of the mesocyclone, such as width and differential velocity: the pre-tornadic focus allows us to eliminate the effects of the tornado itself on the mesocyclone characteristics. GR2Analyst was used to manually analyze 80 tornadic events during the period 1 April 2011 to 1 May 2019. The corresponding tornadoes had damage (EF) ratings ranging from EF0 to EF5, and all were within 100 km of a WSR-88D. A key finding is that the linear regression between the mean, pre-tornadic mesocyclone width and the EF rating of the corresponding tornado yields a coefficient of determination (R2) value of 0.75. This linear relationship is the higher for discrete (supercell) cases (R2=0.82), and lower for QLCS cases (R2=0.37). Overall, we have found that pre-tornadic mesocyclone width tends to be a persistent, relatively time-invariant characteristic that is a good predictor of potential tornado intensity. In contrast, the pre-tornadic mesocyclone intensity (differential velocity) tends to exhibit considerable time variability, and thus would offer less reliability in anticipating tornado intensity. Additionally, the environmental characteristics of each case were analyzed and compared to the pre-tornadic mesocyclone characteristics to better understand the environmental controls on the pre-tornadic mesocyclone width and intensity. Initial findings support a stronger relationship between the pre-tornadic mesocyclone and thermodynamic parameters than with measures of vertical wind shear with a seasonal dependence.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-08-25 without embargo terms","The student, Michael Sessa, accepted the attached license on 2020-05-04 at 14:46.","The student, Michael Sessa, submitted this Thesis for approval on 2020-05-04 at 15:13.","This Thesis was approved for publication on 2020-05-05 at 16:12.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15195 on 2020-08-25 at 17:11:53","Made available in DSpace on 2020-08-26T21:54:51Z (GMT). No. of bitstreams: 2 SESSA-THESIS-2020.pdf: 12523517 bytes, checksum: 626cd3390e9321db663a9fe867d312db (MD5) LICENSE.txt: 4210 bytes, checksum: 7499337eb2a1d1ed01eee3a62132a3cf (MD5) Previous issue date: 2020-05-05"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/107983"],"dc:language":["en"],"dc:rights":["Copyright 2020 Michael Sessa"],"dc:subject":["severe thunderstorms","tornadoes","mesocyclones"],"dc:title":["The observed relationship between tornado intensity and pretornadic mesocyclone characteristics and environments"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Atmospheric Sciences"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:47Z"}