Several annual mesoscale convective complex (MCC) summaries have been compiled since Maddox strictly
defined their criteria in 1980. These previous studies have largely been independent of each other and therefore
have not established the extended spatial and temporal patterns associated with these large, quasi-circular, and,
typically, severe convective systems. This deficiency is primarily due to the difficulty of archiving enough
satellite imagery to accurately record each MCC based on Maddox’s criteria. Consequently, this study utilizes
results from each of the MCC summaries compiled between 1978 and 1999 for the United States in order to
develop a more complete climatology, or description of long-term means and interannual variation, of these
storms. Within the 22-yr period, MCC summaries were compiled for a total of 15 yr. These 15 yr of MCC data
are employed to establish estimated tracks for all MCCs documented and, thereafter, are utilized to determine
MCC populations on a monthly, seasonal, annual, and multiyear basis. Subsequent to developing an extended
climatology of MCCs, the study ascertains the spatial and temporal patterns of MCC rainfall and determines
the precipitation contributions made by MCCs over the central and eastern United States. Results indicate that
during the warm season, significant portions of the Great Plains receive, on average, between 8% and 18% of
their total precipitation from MCC rainfall. However, there is large yearly and even monthly variability in the
location and frequency of MCC events that leads to highly variable precipitation contributions