This report describes the work being done in developing the MESAN system for analyzing surface parameters and clouds. The following parameters are being analyzed: - 2 meter temperature, - precipitation in mm water for 1, 3, 12 and 12 hours accumulation time, and for new snow-cover in cm, - wind speed and direction and gust speed at 10 meter elevation, - visibility, - relative humidity, - total cloud cover, - amount and low clouds, - significant cloud base, - probability of observing significant cloud base, - higt of cloud top, - depth of snow cover, and - sea surface temperature. Hirlam data are normally used as first guess fields. Observatons are taken from synop, metar, Swedish climate stations, satellites, radars and automatic stations. Much work has been devoted to minimizing systematic errors in observations and investigating structure functions of first guess errors. The analys method used is optimal interpolation.