Low-level Stability Analysis of Observed Supercell Environments

Abstract

Lapse rates have long been used to quantify the stability of the environment and aid in the prediction of storms. Low level lapse rates (0-1 km and 0-3 km) specifically have become a tool in understanding the finer processes that distinguish the environment of tornadic supercells from nontornadic supercells. Several previous studies have attempted to analyze these supercell environments through simulations and case studies though limited regular point soundings near supercells and in the inflow region of supercells have made larger studies more difficult to conduct. The largest dataset of this type to date was analyzed by Coniglio and Parker (2020) who utilized 430 Great Plains supercell inflow soundings from multiple field campaigns over a 25 year period to analyze supercell environments. This study expands the Coniglio and Parker (2020) sounding climatology to include soundings from field campaigns in the Southeastern United States. More than 650 soundings within the inflow regions of 147 supercells were binned by distance from the closest supercell. Then low level lapse rates over different depths and distances were calculated to analyze the stability of tornadic and nontornadic supercell environments. Results show that differences in lapse rate values are statistically significant between the Great Plains and Southeast regions which is expected. Furthermore the 0-100 m near storm environment of tornadic supercells is slightly more stable than that of nontornadic supercells even though there is more variability and that the differences in stability between nontornadic and tornadic supercells decrease with greater distance and sampling depth. The 0-100 m layer in the thermodynamic profile could provide additional insights to the inflow environments of supercells in both the Great Plains and Southeast.