The National Weather Radar Testbed (NWRT) located in Norman, Oklahoma was established to demonstrate the potential to simultaneously perform aircraft tracking, wind profiling, and weather surveillance as a multi-mission phased-array radar (MPAR). Since its inception in September of 2003, the system has undergone an extensive engineering evaluation and numerous hardware and software upgrades. Since 2007, a team of scientists, engineers, and software developers at the National Severe Storms Laboratory has been working on enhancing the real-time signal processing functionality of the NWRT to bring it up to par with operational weather radars (such as those in the NEXRAD network) and to demonstrate new capabilities. This development is based on a modern and improved multi-processor/multi-computer signal processing environment which allows the implementation of both traditional and innovative real-time signal processing techniques. These include schemes to effectively remove clutter contamination from meteorological signals, methods to mitigate range and velocity ambiguities, and techniques that allow for faster data collection. This paper presents initial results and describes the roadmap of planned signal processing upgrades for the NWRT that will provide researchers and users with an optimum platform for demonstrating and evaluating the MPAR concept.