Impact of Storm Motion on Interactions between Squall Lines and Urban Areas

Research on the interaction between storms and large urban hubs has been done for the past 50 years now. While many previous studies have focused on unorganized convection, recent research has shown that large cities—particularly those with substantial urban heat islands—can impact more organized storms, such as supercells and squall lines. This project investigates the impact of storm motion on a squall line’s interactions with an urban heat island with a specific focus on how the speed of the storms impacts the modification of the storm. Using an idealized cloud model to run simulations of squall lines passing over a heat island (by creating a circle with a ten-mile radius of a temperature 5℉ greater than the rest of the environment) and the speed of the storms are adjusted to create a faster moving, slower moving, and a control group of storms. These results are compared to simulations without an urban heat island, to show the impact of storm motion on interactions between a squall line and an urban area. Rain mixing ratio, hail/graupel mixing ratio, vertical velocity, and other parameters are examined to determine which storm-scale processes are most impacted by variations in the duration that squall lines interact with the heat island.