By means of several nonconventional observational data, a local severe convective weather even on June 27 2006 in Beijing is studied. The results show that two mesoscale convective cloud clusters and the surface mesoscale convergence line played the triggering role in the heavy rain process, and the urban heat island provided the thermodynamic condition. The measurements of the groundbased 12channl microwave radiometer have good indicative significance to the occurrence of heavy rainfall. The rapid increase (decrease) of Liquid Water Content can be used as an indicator in forecasting the beginning (ending) of heavy rainfall. The continuous observation data from wind profile radar can provide detailed information about a convective system partly, such as the lower and middlelevel wind shears, warm advection, and smallscale lowpressure systems, which are of significance to the formation and maintenance of heavy rainfall.