Volcanic ash can cause air pollution and other environmental impacts. In the last 15 years, 5 volcanoes in Ecuador have produced moderate to large explosive eruptions. Hence, information about the volcanic ash dispersion in forecasting time is priority in Ecuador. For this purpose we build a system based on the WRF and FALL3D, both Eulerian models, used for forecasting meteorology and volcanic ash dispersion respectively. These models solve numerically the full atmospheric and volcanic ash dispersion governing equations, using finite-difference approximations. Currently this system generates information about the potential path of volcanic ash and the affected areas by ash fallout, owing to eruptions at the Tungurahua and Cotopaxi volcanoes. This paper describes the main components of this system, its advantages, and limitations by analyzing the Ecuadorian case study.