Both the frontal cloudiness and the MCS are well reflected in model fields. Isentropes show that in front of the frontal zone of high gradient, an unstable area with equivalent potential temperature decreasing from 324K at the surface to 316K in mid troposphere exists. Convergence is found along the frontal surface, but the most pronounced maximum is situated in the prefrontal area, near the surface, in the area where the MCS develop.