Storm mergers and their role in tornado genesis during the 2011 Joplin storm

Van Leer, Kevin

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https://hdl.handle.net/2142/44134 Copy

Description

Title

Storm mergers and their role in tornado genesis during the 2011 Joplin storm

Author(s)

Van Leer, Kevin

Issue Date

2013-05-24T21:51:48Z

Director of Research (if dissertation) or Advisor (if thesis)

• Wilhelmson, Robert B.
• Jewett, Brian F.

Department of Study

Atmospheric Sciences

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(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.

Graduation Semester

2013-05

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http://hdl.handle.net/2142/44134

Copyright and License Information

Copyright 2013 Kevin Van Leer

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