A Satellite-Based Climatology of Central and Southeastern U.S. Mesoscale Convective Systems

Abstract

Abstract A satellite-based climatology is presented of 9607 mesoscale convective systems (MCSs) that occurred over the central and southeastern United States from 1996 to 2017. This climatology is constructed with a fully automated algorithm based on their cold cloud shields, as observed from infrared images taken by GOES-East satellites. The geographical, seasonal, and diurnal patterns of MCS frequency are evaluated, as are the frequency distributions and seasonal variability of duration and maximum size. MCS duration and maximum size are found to be strongly correlated, with coefficients greater than 0.7. Although previous literature has subclassified MCSs based on size and duration, we find no obvious threshold that cleanly categorizes MCSs. The Plains and Deep South are identified as two regional modes of maximum MCS frequency, accounting for 21% and 18% of MCSs, respectively, and these are found to differ in the direction and speed of the MCSs (means of 16 and 13 m s−1), their distributions of duration and size (means of 12.2 h, 176 000 km2 and 9.6 h, 108 000 km2), their initial growth rates (means of 7.6 and 6.1 km2 s−1), and many aspects of the seasonal cycle. The lifetime patterns of MCS movement and growth are evaluated for the full domain and for the two regional modes. The growth patterns and strong correlation between size and duration allow for a parabolic function to represent the MCS life cycle quite well in summary statistics. We show that this satellite-based climatology supports previous studies identifying favorable environments for mesoscale convective systems.