Interactions Between Squall Lines and Isolated Supercell Thunderstorms via Storm-Generated Perturbations to the Local Environment

South Dakota School Of Mines And Technology, Rapid City SD

Investigators

Abstract

The goal of this research award is to determine how quasi-linear convective systems (squall lines) and supercell thunderstorms interact by modifying their local environments when the two are in close proximity. A combination of observational techniques and numerical simulations will be utilized to: 1) identify common changes to storm structure and intensity that occur as a result of the proximity between the two storm types, and 2) relate these changes to specific environmental perturbations induced by the storms themselves. To date there has been extensive study on the role that background environmental parameters such as instability and wind shear play in modulating convective storm organization and intensity, but it is unclear how storm-generated perturbations to these parameters may influence neighboring convective storms. This represents an important gap in the knowledge base as widespread severe weather outbreaks often see multiple storm types (e.g., squall lines and supercells) evolving in close proximity to one another. Improving our understanding of how these storms interact will provide forecasters with a better idea of what to expect when issuing short-term forecasts and severe weather warnings. Intellectual Merit: As the forecasting community seeks to improve severe weather warnings through new programs such as the Warn on Forecast Initiative, one of the key challenges to overcome is to improve the current understanding of local-scale environmental heterogeneity and its effect on severe thunderstorm evolution. The study will address this challenge by examining the role that localized, storm-induced perturbations to the environment play in modulating severe storm organization and intensity. The results of the work will be used to develop conceptual models to help forecasters understand and anticipate the effects of storm-induced environmental heterogeneity, despite not being able to observe these perturbations directly. Furthermore, much of what is known about convective storm dynamics comes from studies of thunderstorms or convective systems under comparatively "well-behaved" conditions. By investigating how multiple storms interact, the research will be significant as it will provide a test as to whether these generalized conceptual models apply when multiple storms are interacting. Broader Impacts: The "big picture" goal for this research project is to improve short-term severe weather forecasts by improving the understanding of how squall lines and supercell thunderstorms interact. This should lead to more accurate and specific severe weather warnings, and thus a more effective means of protecting life and property during severe weather outbreaks. The project will support two graduate students over the course of the project. In doing so, the project will further the integration of research and education, engaging the students and providing them with valuable first-hand research experience. Results will be disseminated through presentations at national and regional conferences as well as through peer-reviewed journal articles. Additionally, the PI plans to incorporate data and examples into his regular coursework at the South Dakota School of Mines and Technology.