Prepared for Atmospheric Directorate

These working papers were prepared for the timely dissemination of information; this document does not represent the official position of NOARL. An expert system approach to the analysis and short-term prediction of clear air turbulence (CAT) is presented. CAT is defined here as nonconvective turbulence occurring above 18,000 feet. ExperCAT is rule-based, contains a total of 65 rules and has extensive help and explanation features. The system's analysis procedure is to guide a human observer in identifying cloud signatures known to be associated with CAT. ExperCAT forecasts include an estimate of the turbulence intensity and a confidence factor. The user can optionally view the selections entered to arrive at the forecast. Three step-by-step example runs are provided. ly