Idealized Simulations of Supercell Thunderstorms Interacting with the Appalachian Mountains

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Riggin IV, R. (2022). Idealized Simulations of Supercell Thunderstorms Interacting with the Appalachian Mountains. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

The Appalachian Mountains within the eastern United States have a considerable impact on daily weather, including supercell thunderstorms. Forecasters currently lack a comprehensive conceptual model to assist with the decision-making process when supercellular hazards occur in this region which is characterized by complex terrain. While some idealized modeling studies have been conducted that have aided in understanding supercell evolution across idealized terrain configurations and environments, there has yet to be an investigation using more realistic thermodynamic and kinematic profiles. In this study, our research aims to increase understanding of supercell interactions with the Appalachian Mountains, using a combination of both realistic and idealized terrain, and a realistic base-state environment, rooted in model analysis proximity soundings gathered from 62 isolated supercells that traversed the south-central Appalachians between 2008-2019. These storms were tracked via radar and classified based on whether they were maintained following interaction with significant terrain ("crossing") or instead dissipated ("non-crossing"). The present study uses an idealized numerical model to further investigate the environmental controls on crossing versus non-crossing storms. Proximity soundings incorporated into the model base-state were constructed from the upstream/initiation, peak elevation, and downstream/ dissipation points along each observed storm track, with composites calculated at each point for both crossing and non-crossing cases. Several experiments were run while using three different terrain configurations (No Terrain, Idealized, and Realistic Terrain). The base-state environment was horizontal homogeneous (aside from terrain-induced variability) and fixed over time. Three terrain configurations were also tested: no terrain, idealized terrain, and realistic terrain resulting in 12 unique simulations. Results demonstrate four key terrain-induced mechanisms (e.g., terrain blocking, terrain channeling, upslope flow, downslope flow) responsible for modulating simulated supercells as they traverse the south-central Appalachians. In general, these processes lead to kinematic amplifications and reduced thermodynamics at both the meso-γ and meso-β scales. A series of conceptual models are presented to synthesize these terrain-induced mechanisms to aid in operational decision-making processes during future episodes of supercellular convection within the study region.

Details
Author

Riggin IV, Roger

Title

Idealized Simulations of Supercell Thunderstorms Interacting with the Appalachian Mountains

Physical Description

1 online resource (183 pages) : PDF

Date

2022

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

The Appalachian Mountains within the eastern United States have a considerable impact on daily weather, including supercell thunderstorms. Forecasters currently lack a comprehensive conceptual model to assist with the decision-making process when supercellular hazards occur in this region which is characterized by complex terrain. While some idealized modeling studies have been conducted that have aided in understanding supercell evolution across idealized terrain configurations and environments, there has yet to be an investigation using more realistic thermodynamic and kinematic profiles. In this study, our research aims to increase understanding of supercell interactions with the Appalachian Mountains, using a combination of both realistic and idealized terrain, and a realistic base-state environment, rooted in model analysis proximity soundings gathered from 62 isolated supercells that traversed the south-central Appalachians between 2008-2019. These storms were tracked via radar and classified based on whether they were maintained following interaction with significant terrain ("crossing") or instead dissipated ("non-crossing"). The present study uses an idealized numerical model to further investigate the environmental controls on crossing versus non-crossing storms. Proximity soundings incorporated into the model base-state were constructed from the upstream/initiation, peak elevation, and downstream/ dissipation points along each observed storm track, with composites calculated at each point for both crossing and non-crossing cases. Several experiments were run while using three different terrain configurations (No Terrain, Idealized, and Realistic Terrain). The base-state environment was horizontal homogeneous (aside from terrain-induced variability) and fixed over time. Three terrain configurations were also tested: no terrain, idealized terrain, and realistic terrain resulting in 12 unique simulations. Results demonstrate four key terrain-induced mechanisms (e.g., terrain blocking, terrain channeling, upslope flow, downslope flow) responsible for modulating simulated supercells as they traverse the south-central Appalachians. In general, these processes lead to kinematic amplifications and reduced thermodynamics at both the meso-γ and meso-β scales. A series of conceptual models are presented to synthesize these terrain-induced mechanisms to aid in operational decision-making processes during future episodes of supercellular convection within the study region.

Genre

masters theses

Subjects--Topics

Meteorology
Geophysics
Geography

Degree

M.S.

Keywords

Appalachians Mountains
Forecasting
Mesoscale Meteorology
Mountain Meteorology
Numerical Modeling
Supercells

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, 2022.

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Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

RigginIV_uncc_0694N_13247

Permalink

http://hdl.handle.net/20.500.13093/etd:3148