A mesoscale, real-time, four-dimensional data assimilation (RT-FDDA) and short-term forecasting system has been developed for the U.S. Army Test and Evaluation Command (ATEC) at the Dugway Proving Ground (DPG) in Utah. This MM5-based analysis and forecast system (described in Cram et al., 2001 WAF/NWP separate submission) provides a continuous series of updated 3-dimensional analyses and a new 12-hr forecast on 3 domains (30 km, 10km, and 3.3 km grid spacings) every 3 hours in real-time. The system uses many diverse data sets available over the region: standard surface and upper air observations, special surface observations, the University of Utah MesoWest observations (extensive western U.S. mesonet), DPG local surface observations, DPG profilers and RASS instrumentation, and NESDIS GOES wind vectors. The NESDIS GOES wind vectors are a unique data set in that their horizontal and vertical locations are never pre-determined, and there is always a very uneven distribution - ranging from dense coverage in some local regions to no coverage in other regions. The impact of the GOES wind data will be measured for a particular case by comparing parallel versions of the RT-FDDA system, with and without the NESDIS data set, with the systems' error calculated against the rawinsonde and surface observation data sets.