Investigating the longevity of significant-tornado producing supercells

All 1,515 significant (EF-2+) tornadoes and their environments between 2008 and 2018 in the United States are examined, with a focus on parent supercell thunderstorm longevity. Almost all significant tornadoes are produced by discrete supercells (66%) or clusters (27%), and they are most common in the Plains or Southeast between March and June, with a small secondary peak in November in the Southeast. Bulk wind shear and storm-relative helicity (SRH) are moderately correlated (r ≈ 0.35) with the total time that a supercell is discrete, the total number of significant tornadoes produced by a storm, and the total tornado path length associated with a storm. There is no correlation between storm longevity and any thermodynamic variable. Long-lived (≥ 4 hours) supercells are most frequent in the Southeast, where shear and SRH are typically greatest. Additionally, SRH is roughly 50-70 m2 s-2 greater for the longer-lived supercells (≥ 75th percentile) than for the shorter-lived ones. Another key finding is that excessive (≥ 90th percentile) backing or veering of the wind shear vector above 1 km above ground level (AGL) is detrimental to supercell longevity.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Housenga, Rylan J

Contributors dc:contributor

• Frame, Jeffrey
• Sriver, Ryan
• Trapp, Robert J.

• supercell
• longevity
• significant tornado

Statement dc:rights

• Copyright 2022 Rylan Housenga

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115443

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115443