INVESTIGATION OF THE ENVIRONMENTAL INFLUENCES RELATED TO THE PRECIPITATION STRUCTURE OF SUPERCELL THUNDERSTORMS AND THEIR EVOLUTION

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Sirico, R. (2020). INVESTIGATION OF THE ENVIRONMENTAL INFLUENCES RELATED TO THE PRECIPITATION STRUCTURE OF SUPERCELL THUNDERSTORMS AND THEIR EVOLUTION. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

The precipitation structure of supercell thunderstorms (e.g., low-precipitation(LP), classic (CL), high-precipitation (HP)) has been associated with differing severeweather threats (wind, hail, or tornadoes) to the public, thus motivating work examiningthe causes for these supercell categories. Previous research has demonstrated that theprecipitation structure of these storms is impacted by both the kinematic andthermodynamic profiles within their inflow environments; in particular, it has beenhypothesized via analysis of a set of observed supercells across the precipitation spectrumthat the upper-level wind profile is of paramount importance, due to the ability of thesewinds to transport hydrometeors close to (i.e., weak winds leading to HP) or farther away(i.e., strong winds leading to LP) from the updraft (Rasmussen and Straka 1998). However,a recent idealized modeling study conducted by Warren et al. (2017) has found theopposite association, which suggests additional investigation is necessary.The present study uses an automated tracking algorithm to identify and classify104 supercell thunderstorms into either LP/CL or HP categories; 66 were identified asLP/CL and 38 as HP. Model-derived soundings were then used to describe the inflowenvironments of these storms throughout their lifetimes. Distributions of numerousthermodynamic and kinematic parameters were created to compare the two dominantsupercell categories using statistical significance tests. Following these statistical comparisons, it was clear that a number of differences were present between LP/CL andHP environments. In particular, the kinematic profiles of LP/CL supercells tended tocontain stronger bulk shear, storm-relative helicity, and stronger upper-level windscompared to HP supercells, consistent with the prior observational study of Rasmussenand Straka (1998). However, the LP/CL wind profiles also contained veering winds aloft,which did provide consistency with Warren et al. (2017). Along with these kinematicdifferences, variations in the thermodynamic profile also proved to be important; HPstorms exhibited significantly higher lifted condensation level (LCL) and level of freeconvection (LFC) heights, in addition to lower convective available potential energy(CAPE).Many of the key inflow environmental differences could be tied to the synopticset-up for each of the given precipitation modes. Notably, LP/CL storms often findthemselves in much stronger synoptically forced environments, evident at multiple levelsin the atmosphere (e.g., jet-level [300 hPa], 500 hPa, surface). Overall, the broaderconsistency of the present study with other prior observational studies, as opposed to therecent modeling studies, suggests that additional work is still needed to betterunderstand the interplay of variations in kinematic and thermodynamic profiles inproducing varying precipitation structures within supercells.

Details
Author

Sirico, Richard

Title

INVESTIGATION OF THE ENVIRONMENTAL INFLUENCES RELATED TO THE PRECIPITATION STRUCTURE OF SUPERCELL THUNDERSTORMS AND THEIR EVOLUTION

Physical Description

1 online resource (138 pages) : PDF

Date

2020

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

The precipitation structure of supercell thunderstorms (e.g., low-precipitation(LP), classic (CL), high-precipitation (HP)) has been associated with differing severeweather threats (wind, hail, or tornadoes) to the public, thus motivating work examiningthe causes for these supercell categories. Previous research has demonstrated that theprecipitation structure of these storms is impacted by both the kinematic andthermodynamic profiles within their inflow environments; in particular, it has beenhypothesized via analysis of a set of observed supercells across the precipitation spectrumthat the upper-level wind profile is of paramount importance, due to the ability of thesewinds to transport hydrometeors close to (i.e., weak winds leading to HP) or farther away(i.e., strong winds leading to LP) from the updraft (Rasmussen and Straka 1998). However,a recent idealized modeling study conducted by Warren et al. (2017) has found theopposite association, which suggests additional investigation is necessary.The present study uses an automated tracking algorithm to identify and classify104 supercell thunderstorms into either LP/CL or HP categories; 66 were identified asLP/CL and 38 as HP. Model-derived soundings were then used to describe the inflowenvironments of these storms throughout their lifetimes. Distributions of numerousthermodynamic and kinematic parameters were created to compare the two dominantsupercell categories using statistical significance tests. Following these statistical comparisons, it was clear that a number of differences were present between LP/CL andHP environments. In particular, the kinematic profiles of LP/CL supercells tended tocontain stronger bulk shear, storm-relative helicity, and stronger upper-level windscompared to HP supercells, consistent with the prior observational study of Rasmussenand Straka (1998). However, the LP/CL wind profiles also contained veering winds aloft,which did provide consistency with Warren et al. (2017). Along with these kinematicdifferences, variations in the thermodynamic profile also proved to be important; HPstorms exhibited significantly higher lifted condensation level (LCL) and level of freeconvection (LFC) heights, in addition to lower convective available potential energy(CAPE).Many of the key inflow environmental differences could be tied to the synopticset-up for each of the given precipitation modes. Notably, LP/CL storms often findthemselves in much stronger synoptically forced environments, evident at multiple levelsin the atmosphere (e.g., jet-level [300 hPa], 500 hPa, surface). Overall, the broaderconsistency of the present study with other prior observational studies, as opposed to therecent modeling studies, suggests that additional work is still needed to betterunderstand the interplay of variations in kinematic and thermodynamic profiles inproducing varying precipitation structures within supercells.

Genre

masters theses

Subjects--Topics

Meteorology

Degree

M.S.

Keywords

Environment
Hazards
Observational
Sounding
Supercell
Tracking Algorithm

Subject Area

Earth Sciences

Advisor(s)

Davenport, Casey

Committee Members

Eastin, Matthew
Shirley, Terry

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2020.

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Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Sirico_uncc_0694N_12403

Permalink

http://hdl.handle.net/20.500.13093/etd:2515