Design highlights, system performance and operational use of the Portable Automated Mesonet (PAM) are featured. PAM consists of a trailer-mounted base station and a network of remote sampling stations for surface mesoscale research. PAM differs from unautomated systems in that the data are sampled synchronously, averaged locally and transmitted digitally via a telemetry link to the base station where real-time data from the entire network are displayed. The base station uses minicomputer control for polling remotes, logging data, checking data quality and displaying data. Displays include tabular listings, time plots, vector wind plots and contours. Remote stations measure pressure, temperature, humidity, rain, wind speed and wind direction, and include flexibility for future expansion. A programmable microprocessor at each remote station controls communications, data sampling and data averaging. Averaged data are reported to the base station when the base station interrogates the remote station (typically once a minute). System performance was evaluated in a group intercomparison experiment prior to field operation in support of the National Hail Research Experiment (NHRE '76). Real-time display of PAM was used to identify surface mesoscale circulations influencing thunderstorm development during NHRE '76.