Assessing the impact of the nocturnal transition on the lifetime and evolution of supercell thunderstorms in the Great Plains.

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Gropp, M. (2017). Assessing the impact of the nocturnal transition on the lifetime and evolution of supercell thunderstorms in the Great Plains. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

Predicting the evolution of supercell thunderstorms during and after the eveningtransition is a known challenge due to an incomplete understanding of how they evolve inresponse to associated environmental changes. As the low-level environment cools andstabilizes, supercells can dissipate, merge with other convection, grow upscale, or besustained as either a surface-based or elevated supercell. The goal of this study istherefore to better predict how supercells will evolve during the evening transition byfocusing on trends in environmental parameters that will lead to increased skill inforecasting. To quantify the connection between storm evolution and environmentalchanges during the nocturnal transition, a large number of initially isolated Great Plainssupercell thunderstorms occurring between 2005 and 2016 are examined. Each supercellis categorized as either maintained, dissipating, growing upscale, or merging. Changes inthe inflow environment are quantified using hourly RUC and RAP proximity soundingsbetween one hour prior to local sunset time and five hours post sunset. Using thesesoundings, numerous thermodynamic and kinematic parameters are derived, includingsurface-based and most unstable CAPE and CIN, and low-level and deep-layer shear andstorm-relative helicity. In general, the differences were large between evolutioncategories, but varied depending on the comparison; each classification existed in aunique set of kinematic and thermodynamic parameters. Statistical tests comparing trendsand distributions of these parameters were most notable for maintained versus dissipated ivcases; storm-relative helicity was identified as a key parameter in distinguishing thesecase types, with maintained supercells containing significantly higher storm-relativehelicity values during the nocturnal transition. The benefit of stronger, sustained storm relativehelicity values is inferred to help maintain a robust rotating updraft despiteincreasing stability, while a decrease (as seen in other supercell evolution categories)would lead to a loss of supercellular characteristics.

Details
Author

Gropp, Matthew

Title

Assessing the impact of the nocturnal transition on the lifetime and evolution of supercell thunderstorms in the Great Plains.

Physical Description

1 online resource (155 pages) : PDF

Date

2017

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Predicting the evolution of supercell thunderstorms during and after the eveningtransition is a known challenge due to an incomplete understanding of how they evolve inresponse to associated environmental changes. As the low-level environment cools andstabilizes, supercells can dissipate, merge with other convection, grow upscale, or besustained as either a surface-based or elevated supercell. The goal of this study istherefore to better predict how supercells will evolve during the evening transition byfocusing on trends in environmental parameters that will lead to increased skill inforecasting. To quantify the connection between storm evolution and environmentalchanges during the nocturnal transition, a large number of initially isolated Great Plainssupercell thunderstorms occurring between 2005 and 2016 are examined. Each supercellis categorized as either maintained, dissipating, growing upscale, or merging. Changes inthe inflow environment are quantified using hourly RUC and RAP proximity soundingsbetween one hour prior to local sunset time and five hours post sunset. Using thesesoundings, numerous thermodynamic and kinematic parameters are derived, includingsurface-based and most unstable CAPE and CIN, and low-level and deep-layer shear andstorm-relative helicity. In general, the differences were large between evolutioncategories, but varied depending on the comparison; each classification existed in aunique set of kinematic and thermodynamic parameters. Statistical tests comparing trendsand distributions of these parameters were most notable for maintained versus dissipated ivcases; storm-relative helicity was identified as a key parameter in distinguishing thesecase types, with maintained supercells containing significantly higher storm-relativehelicity values during the nocturnal transition. The benefit of stronger, sustained storm relativehelicity values is inferred to help maintain a robust rotating updraft despiteincreasing stability, while a decrease (as seen in other supercell evolution categories)would lead to a loss of supercellular characteristics.

Genre

masters theses

Subjects--Topics

Meteorology

Degree

M.S.

Subject Area

Earth Sciences

Advisor(s)

Davenport, Casey

Committee Members

Shirley, Terry
Eastin, Matthew

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2017.

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This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). For additional information, see http://rightsstatements.org/page/InC/1.0/.

Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Gropp_uncc_0694N_11403

Permalink

http://hdl.handle.net/20.500.13093/etd:254