Cell development and merger in an Illinois thunderstorm observed by Doppler radar

Two characteristic separations were found between the newly formed cells and the parent thunderstorm, with the closer cells forming in response to the collapse of an active cell and the more distant cells forming in a previously existing storm-modified area characterized by mesoscale convergence and rain cooled air. The manner in which these cells evolved appeared to be partially related to differences in the environment in which they formed. Later in the life cycle of the storm, two cells which initially formed further away from the main storm appeared more like classical "strongly evolving' cells. It is proposed that the intercell flow is a result of radial outflow observed at heights above the maximum updraft level in the actively growing echoes. The strengthening of the reflectivity bridge may have been the result of both particle transfer and environmental modification brought about by this radial outflow. -from Authors