The Federal Aviation Administration (FAA) is developing a number of terminal weather sensors and a terminal weather information system which can make important contributions toward an operational wake vortex advisory service. Although these systems have been developed to meet other important weather information needs, their existence/development offers the possibility of a more cost effective wake vortex advisory system than would be possible with a standalone system such as was tested in the 1970's. Specifically, we postulate an advisory system in which the aircraft separation during IFR conditions is adjusted to account for the advection of vortices by the wind on the approach path and/or the breakup of vortices due to air instability and in which the desired aircraft separation is achieved by the Terminal Air Traffic Automation (TATCA) system. When reduced separations are obtained with such a system, it is important to be able to anticipate that the winds/vortex stability in the terminal area will continue to meet the reduced spacing criteria for an appropriate time interval (e.g., at least 15 minutes) in the future.