Three case study days (9, 13 and 23 August 1971) of Project METROMEX were selected on the merit of available data to investigate possible urban-induced influences on convective cloud activity. Data included observations from meteorologically equipped aircraft and mobile units, radiosondes and pilot balloons, lidar, surface temperature and dew point recording network, radar and 35-mm photographs. Analysis of the data revealed regions where convective cloud activity was inhibited by the presence of an elevated thermally stable layer, while simultaneously, other regions showed cumulus development. Using a dimensional similitude analysis of a fluidal model, it was found that the atmospheric system may be capable of exhibiting elevated warming via turbulent entrainment of warm air downward through the elevated stable layer. Aerosol heating was also considered as a mechanism which may produce elevated heating. (Modified author abstract)