In this report, we use pencil-beam Doppler weather radar data, combined with on-airport ground clutter measurements, to analyze the performance of the six-level weather channel in the next generation airport surveillance radar, the ASR-9. A key tool was a computer procedure that used these data to simulate the output of the ASR-9's weather channel, including effects of the radar's fan-shaped elevation beams, short coherent processing intervals and ground clutter filters. Our initial analysis indicates that: (a) the combination of high-pass Doppler filters and spatial/temporal smoothing should normally prevent ground clutter from having a significant effect on the controllers' weather display; (b) the spatial/temporal smoothing processor will result in weather contours that are statistically stable on a to-scan basis, reinforcing controller confidence in the validity of the data; (c) relative to the coarse resolution imposed by use of the NWS levels, accurate two-dimensional parameterizations of storm reflectivity can be estimated. Our assessment indicates that the ASR-9's weather reflectivity maps should be reliable. The radar will be widely deployed at significant air terminals, and will provide a combination of high update rate and large volumetric coverage not available from other sensors. These attributes should lead the ASR-9 becoming an important component of the Federal Aviation Agency's modernized weather nowcasting system.