A Comparison of the Life Cycles of Elevated and Surface-Based Convection

This work uses Nexrad level 2 radar data to examine the differences in life cycles and storm characteristics of elevated convective cells and surface-based ones. Eight cases of each type were selected from eastern KS, southeastern NE, southern IA and MO during the period 2007-2010. These cases were previously selected for a study examining the correlation between convective rainfall rates and lightning flashes; in the previous study, the cases were classified as either elevated or surface-based. Each case was also categorized based on the mesoscale dynamics of its stratiform precipitation shield (trailing, leading or parallel).

Using reflectivity CAPPIs at 1 km above the radar, echo top heights for the 30-dBZ reflectivity surface and maximum convergence at 1 km, 2 km, below 3 km, and between 3 km and 7 km individual storm cell life cycle characteristics were observed. Results suggest higher reflectivities and lower echo top heights in elevated thunderstorms, indicating heavier rainfall rates. Elevated cells exhibited stronger convergence values at all levels in the first 30-40 minutes of the cell’s lifetime, reflecting the rapid development of elevated convection, while the surface-based cells had more constant convergence values throughout the cell’s lifecycle. Finally, elevated storm cells tended to last slightly longer than surface-based cells, but surface-based cells had greater spread in duration, as the longest lasting cells were surface-based.