This paper describes an enhanced weather processor for the Federal Aviation Administration's Airport Surveillance Radar (ASR-9) that will include Doppler wind estimation for the detection of low altitude wind shear, scan-to-scan tracking to provide estimates of the speed and direction of storm movement and suppression of spurious weather reports currently generated by the ASR-9's six-level weather channel during episodes of anamalous radar energy propagation (AP). This ASR-9 Wind Shear Processor (WSP) will be implemented as a retrofit to the ASR-9 through the addition of interfaces, receiving chain hardware and high-speed digital processing and display equipment. Thunderstorm activity in terminal airspace (the volume extending approximately 30 nmi from an airport and to 15,000 feet altitude) is an obvious safety issue and makes a significant overall contribution to delay in the United States commercial aviation industry. Associated low-altitude wind shear has been identified as the primary cause of a number of air carrier accidents, involving almost 600 fatalities. Correlations of aircraft arrival and takeoff delay with associated weather conditions suggest that thunderstorm activity may account for 40 to 50 percent of serious delay within the United States. The WSP modification to the ASR-9 will provide the functional capabilities of the Terminal Doppler Weather Radar (TDWR) at airports whose operation levels and/or thunderstorm exposures do not justify the costs of the dedicated radar. Field testing of a prototype version of the ASR-9 WSP has confirmed that the weather information products it generates are accurate and are operationally useful in an Air Traffic Control (ATC) environment.