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Title:Storm mergers and their role in tornado genesis during the 2011 Joplin storm
Author(s):Van Leer, Kevin
Advisor(s):Wilhelmson, Robert B.; Jewett, Brian F.
Department / Program:Atmospheric Sciences
Discipline:Atmospheric Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):Tornadoes
Supercells
Joplin
Tornado Genesis
Storm Mergers
Severe Weather
Abstract:The relationship between storm mergers and tornado formation can result in local conditions more favorable for rapid intensification of vertical vorticity at the surface than found in the surrounding environment. Following the work of Lemon (1976) and Lee et al. (2006), this study uses high-resolution WRF simulations to simulate and understand the significance of storm mergers in subsequent intensification of the parent rotating updraft (mesocyclone) and tornadic vortex in the 22 May 2011 Joplin, MO case. This case was noted for the rapid evolution of the storm from tornado formation (tornadogenesis) to peak intensity in relation to the merging of cells in the rear-flank region of the parent storm. In an effort to identify the importance of the mergers in the tornadogenesis process, casestudy WRF simulations are used to reproduce behavior observed in the event. An in-depth qualitative and quantitative analysis of the relationships between internal storm dynamical processes, such as precipitation loading and increased surface convergence, is performed. Three-dimensional visualization is utilized to identify spatial and temporal relationships between stormscale processes. Sensitivity tests, including the artificial removal or alteration of the merging cells in the model, modify the storm evolution and allow the quantification of the mergers’ effects. This study pursued a goal of identifying storm scale processes resulting from storm mergers that enhance, weaken or otherwise modulate tornado development in supercell storms.
Issue Date:2013-05-24
URI:http://hdl.handle.net/2142/44134
Rights Information:Copyright 2013 Kevin Van Leer
Date Available in IDEALS:2013-05-24
Date Deposited:2013-05


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