Cumulus convective clouds provide an important link between the mixed layer and the upper levels of the troposphere. Fresh boundary layer pollutants emitted naturally and anthropogenically can be transported to high altitudes during deep convective activity. The convective transport process is complex and poorly understood at present. One of the objectives of the North Dakota Thunderstorm Project, a joint field measurement program conducted near Bismarck North Dakota during June and July 1989 (Boe et al. 1989), was to document vertical transport by cumulonimbus type clouds. A tracer, SF(sub 6), was used to follow the movement of air from cloud base to higher elevations. The case study described in the paper is from a developing, vigorous cumulus cloud that was a part of a larger Mesoscale Convective System. Data used here includes observations from the NCAR CP3 Doppler radar and from the University of Wyoming King air research aircraft.