The effects of multiple fire plumes in a stably stratified atmosphere with a uniform wind are investigated. A parabolized approximation of the steady-state Navier-Stokes equations obtained by replacing the windward velocity component with the ambient wind speed is the basis of the model. Lagrangian particles are used to visualize the flow, account for atmospheric fluctuations, and determine the smoke concentration field. Multiple-plume interactions can push particulate up to altitudes exceeding that of an equivalent single plume. A parametric study based on separation and heat release rates is performed for two plumes. The most dramatic increases in plume rise and spread are found for in-line plumes, parallel to the wind direction. Multiple-plume interactions can yield nonuniformities in the smoke concentration field that differ substantially from that predicted by Gaussian models.