The convex-shaped coastline just west of Tallahassee, Florida, is perceived to have an adverse influence on the intensity of non-supercell squall lines as they approach the city. Although this is a much discussed topic in Tallahassee, no research concerning the effects of coastline shape on squall lines apparently has been completed locally or elsewhere. A case-study approach for the Tallahassee area would be premature without a sound fundamental conceptual model upon which to build. Thus, the primary objective of our current study is to develop conceptual models of how coastlines affect squall lines using mesoscale numerical modeling. This is accomplished by two-dimensional numerical model simulations using the Advanced Regional Prediction System Model (ARPS). First, squall lines are simulated for a wide range of wind shear profiles without radiation and surface physics parameterization. These simulations are necessary to test the model's performance and provide a control for later simulations. The second phase tests the effect of a land/sea interface on squall lines when radiation and surface physics are included. This is accomplished by introducing a theoretical coastline within the two-dimensional domain. This configuration simulates a squall line that is moving either onshore or offshore during diurnal temperature extremes. Results of the simulations reveal how coastal circulations and temperature distributions affect the intensity and other characteristics of a squall line. For example, nocturnal cooling on the land portion of the model domain is shown to adversely affect squall lines moving onshore. Results also show that squall lines occurring during larger wind shear profiles are more susceptible to varying surface temperature, particularly a nocturnal inversion over land. The results indicate that three-dimensional modeling is needed to completely resolve many of the processes involved. Nevertheless, the results of the two-dimensional simulations are useful in providing information that is needed to develop a fundamental conceptual model of squall line-coastal interaction.