{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/108035"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/108035","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Analyses of quasi-linear convective system tornado characteristics, environments, and genesis mechanisms","abstract":"The primary goal of this research was to quantify occurrence frequencies of the two main proposed mechanisms of tornadogenesis in quasi-linear convective systems (QLCSs), namely, tilting and stretching (T&S) and HSI and stretching (H&S). This research then sought to investigate differences and similarities between the characteristics of the T&S- and H&S- associated tornadoes and their supporting environments. A combined Doppler radar, tornado report, and environment dataset was compiled for this purpose. Lastly, this research aimed to quantify National Weather Service (NWS) warning performance for both mechanisms. From a strict consideration of only the first tornado generated by a QLCS during 2016-2018, 152 QLCS tornado cases were identified. Of these, 145 where determined to be the result of T&S, and 7 where determined to be the result of H&S, indicating that T&S is far more likely to be the tornadogenesis mechanism of the first tornado in a QLCS. QLCS tornadoes tended to be focused in the southern U.S. during winter and spring and the northern U.S. during summer. Tornadogenesis through H&S occurred relatively earlier in the year and earlier in the day, and resulted in relatively weaker tornadoes than did tornadogenesis through T&S. Environmental analysis showed that H&S environments had relatively lower values of CAPE and relatively higher values of low-level shear compared to T&S. Analysis of NWS warnings showed that H&S tornadoes had relatively lower tornado warning frequencies than did T&S tornadoes, while having, on average, half the warning lead time. Finally, based on a consideration of pre-tornadic Doppler radar data, it was found that H&S low-level circulations tended to form more rapidly than did T&S low-level circulations, thus providing less potential lead time.","abstract_html":"The primary goal of this research was to quantify occurrence frequencies of the two main proposed mechanisms of tornadogenesis in quasi-linear convective systems (QLCSs), namely, tilting and stretching (T&S) and HSI and stretching (H&S). This research then sought to investigate differences and similarities between the characteristics of the T&S- and H&S- associated tornadoes and their supporting environments. A combined Doppler radar, tornado report, and environment dataset was compiled for this purpose. Lastly, this research aimed to quantify National Weather Service (NWS) warning performance for both mechanisms. From a strict consideration of only the first tornado generated by a QLCS during 2016-2018, 152 QLCS tornado cases were identified. Of these, 145 where determined to be the result of T&S, and 7 where determined to be the result of H&S, indicating that T&S is far more likely to be the tornadogenesis mechanism of the first tornado in a QLCS. QLCS tornadoes tended to be focused in the southern U.S. during winter and spring and the northern U.S. during summer. Tornadogenesis through H&S occurred relatively earlier in the year and earlier in the day, and resulted in relatively weaker tornadoes than did tornadogenesis through T&S. Environmental analysis showed that H&S environments had relatively lower values of CAPE and relatively higher values of low-level shear compared to T&S. Analysis of NWS warnings showed that H&S tornadoes had relatively lower tornado warning frequencies than did T&S tornadoes, while having, on average, half the warning lead time. Finally, based on a consideration of pre-tornadic Doppler radar data, it was found that H&S low-level circulations tended to form more rapidly than did T&S low-level circulations, thus providing less potential lead time.","abstract_has_math":false,"creators":["Chehak, Devin Andrew"],"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"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2020,"date_issued":"2020-08-26T21:58:02Z","date_published":"2020-08-26T21:58:02Z","updated_at":"2026-07-22T22:24:47Z","subjects":["Severe Weather, Tornado, QLCS, Squall Line, MCS"],"languages":["en"],"rights":["Copyright 2020 Devin Chehak"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/108035","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Trapp, Robert"]},{"key":"dc:creator","label":"Author","values":["Chehak, Devin Andrew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2020-08-26T21:58:02Z","2020-05-13","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 Weather, Tornado, QLCS, Squall Line, MCS"]}]},{"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 Devin Chehak"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/108035"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The primary goal of this research was to quantify occurrence frequencies of the two main proposed mechanisms of tornadogenesis in quasi-linear convective systems (QLCSs), namely, tilting and stretching (T&S) and HSI and stretching (H&S). This research then sought to investigate differences and similarities between the characteristics of the T&S- and H&S- associated tornadoes and their supporting environments. A combined Doppler radar, tornado report, and environment dataset was compiled for this purpose. Lastly, this research aimed to quantify National Weather Service (NWS) warning performance for both mechanisms. From a strict consideration of only the first tornado generated by a QLCS during 2016-2018, 152 QLCS tornado cases were identified. Of these, 145 where determined to be the result of T&S, and 7 where determined to be the result of H&S, indicating that T&S is far more likely to be the tornadogenesis mechanism of the first tornado in a QLCS. QLCS tornadoes tended to be focused in the southern U.S. during winter and spring and the northern U.S. during summer. Tornadogenesis through H&S occurred relatively earlier in the year and earlier in the day, and resulted in relatively weaker tornadoes than did tornadogenesis through T&S. Environmental analysis showed that H&S environments had relatively lower values of CAPE and relatively higher values of low-level shear compared to T&S. Analysis of NWS warnings showed that H&S tornadoes had relatively lower tornado warning frequencies than did T&S tornadoes, while having, on average, half the warning lead time. Finally, based on a consideration of pre-tornadic Doppler radar data, it was found that H&S low-level circulations tended to form more rapidly than did T&S low-level circulations, thus providing less potential lead time.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-08-25 without embargo terms","The student, Devin Chehak, accepted the attached license on 2020-05-11 at 13:46.","The student, Devin Chehak, submitted this Thesis for approval on 2020-05-11 at 13:55.","This Thesis was approved for publication on 2020-05-13 at 16:49.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15326 on 2020-08-25 at 17:13:57","Made available in DSpace on 2020-08-26T21:58:02Z (GMT). No. of bitstreams: 2 CHEHAK-THESIS-2020.pdf: 7078131 bytes, checksum: 2ff572f64c9c5317bd60a5c0b7946cc0 (MD5) LICENSE.txt: 4209 bytes, checksum: 60b5a56eb6aed482c24a2718a33d2411 (MD5) Previous issue date: 2020-05-13"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Analyses of quasi-linear convective system tornado characteristics, environments, and genesis mechanisms"]}]}],"canonical_facts":{"dc:contributor":["Trapp, Robert"],"dc:creator":["Chehak, Devin Andrew"],"dc:date":["2020-08-26T21:58:02Z","2020-05-13","2020-05"],"dc:description":["The primary goal of this research was to quantify occurrence frequencies of the two main proposed mechanisms of tornadogenesis in quasi-linear convective systems (QLCSs), namely, tilting and stretching (T&S) and HSI and stretching (H&S). This research then sought to investigate differences and similarities between the characteristics of the T&S- and H&S- associated tornadoes and their supporting environments. A combined Doppler radar, tornado report, and environment dataset was compiled for this purpose. Lastly, this research aimed to quantify National Weather Service (NWS) warning performance for both mechanisms. From a strict consideration of only the first tornado generated by a QLCS during 2016-2018, 152 QLCS tornado cases were identified. Of these, 145 where determined to be the result of T&S, and 7 where determined to be the result of H&S, indicating that T&S is far more likely to be the tornadogenesis mechanism of the first tornado in a QLCS. QLCS tornadoes tended to be focused in the southern U.S. during winter and spring and the northern U.S. during summer. Tornadogenesis through H&S occurred relatively earlier in the year and earlier in the day, and resulted in relatively weaker tornadoes than did tornadogenesis through T&S. Environmental analysis showed that H&S environments had relatively lower values of CAPE and relatively higher values of low-level shear compared to T&S. Analysis of NWS warnings showed that H&S tornadoes had relatively lower tornado warning frequencies than did T&S tornadoes, while having, on average, half the warning lead time. Finally, based on a consideration of pre-tornadic Doppler radar data, it was found that H&S low-level circulations tended to form more rapidly than did T&S low-level circulations, thus providing less potential lead time.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2020-08-25 without embargo terms","The student, Devin Chehak, accepted the attached license on 2020-05-11 at 13:46.","The student, Devin Chehak, submitted this Thesis for approval on 2020-05-11 at 13:55.","This Thesis was approved for publication on 2020-05-13 at 16:49.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15326 on 2020-08-25 at 17:13:57","Made available in DSpace on 2020-08-26T21:58:02Z (GMT). No. of bitstreams: 2 CHEHAK-THESIS-2020.pdf: 7078131 bytes, checksum: 2ff572f64c9c5317bd60a5c0b7946cc0 (MD5) LICENSE.txt: 4209 bytes, checksum: 60b5a56eb6aed482c24a2718a33d2411 (MD5) Previous issue date: 2020-05-13"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/108035"],"dc:language":["en"],"dc:rights":["Copyright 2020 Devin Chehak"],"dc:subject":["Severe Weather, Tornado, QLCS, Squall Line, MCS"],"dc:title":["Analyses of quasi-linear convective system tornado characteristics, environments, and genesis mechanisms"],"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"}