Simulations of an organized convective system interacting with Louisville, KY were conducted to determine the impact of urban heat island (UHI) magnitude on the structure and intensity of convective storms. Four different simulations are presented: A control, two simulations in which the UHI is enhanced through observational nudging, and a simulation where the urban area is removed (no-city simulation). Results show that the downwind enhancement of convective cells increases with increasing UHI magnitude. However, large differences are also apparent between the control and the no-city simulations. This suggests that surface convergence caused by flow obstruction may be as influential to the modification of organized storms as the UHI, although the locations of these two effects are offset. Convergence due to flow obstruction is most noticeable on the upwind edge and over the center of the city while the impact of UHI magnitude is most noticeable on the downwind edge of the city.