At ECMWF a new synthesis of the in-situ and remotely-sensed measurements made during the Special Observing Period (SOP) of the Mesoscale Alpine Programme (MAP) is performed using the latest 12-hr-4D-Var global data assimilation system. The MAP Re-Analysis will produce analyses with three hourly frequency throughout the period. The products will be of high temporal and spatial resolution, with a grid-spacing close to 40km in the horizontal and with sixty levels in the vertical located between the surface and a height of about 65km. The basic analysed variables will include not only the conventional meteorological wind, temperature and humidity fields, but also model products currently available in the ERA-40 Re-Analysis. A sophisticated archival/retrieval system will be used to store the results and make them widely available.