Several major aircraft accidents have been attributed to low-altitude wind shears, which are normally caused by microbursts or gust fronts. Terminal Doppler Weather Radar (TDWR) systems are being installed near major airports for the detection of low-altitude wind shears. In order to develop a TDWR system further, low-altitude wind shears were numerically simulated in this study. The basic equations, which contain prognostic equations for air velocity, pressure, temperature, water vapor, and rainwater, were solved using a finite difference scheme. A terrain-following coordinate transformation was employed to simulate terrain effects. The simulation results are presented in this paper.