The quality of astronomical observations is strongly related to the quality properties of the atmosphere. This parameter is important for the determination of the observation modes, and for observation program, the socalled flexible scheduling. We propose to present the implementation of the WRF model in order to routinely and automatically forecast the optical conditions. The purpose of our study is to predict 24 hours ahead the optical conditions above an observatory to optimize the observation time, not only the meteorological conditions at ground level, but also the vertical distribution of the optical turbulence and the wind speed, i.e the so-called astronomical seeing. The seeing is computed using the Trinquet-Vernin model coupled with the vertical profiles of the wind shear and the potential temperature predicted by the WRF model. We made a comparison between the WRF output and the in situ measurements made with the DIMM and an automatic weather station above the Observatorio del Roque de los Muchachos, Canary Island. Here we show that the increase of resolution in both the terrain model and 3D grid yields better forecast when compared with in situ optical and meteorological observations.