Evaluation of precipitation forecasts from MM5 for the Alps and the Po' Valley during the MAP IOPs indicates better performance over the mountains than over the adjacent plain. In fact several cases of locally heavy rainfall in the Po' Valley were completely missed by the model. In cases of southerly synoptic-scale flow, the Po' Valley is in the lee of the Apennines and, as generally appreciated, orographic effects on precipitation on the lee sides are particularly difficult for a model to capture. To explore these model deficiencies within the MAP context, MM5 simulations for all the IOPs are performed using an idealized topography representing the Apennines. Evaluation of the model forecast (as measured by equitable score and bias) to variations of the height and slope of the idealized Apennines, indicate the importance of Apennine lee-side effects on the Po' Valley forecast.