Rachael Cross

Convective Meteorology (Mesoscale Dynamics)

Rachael Cross

Analysis of Dual-Polarimeteric Radar Signatures in Tornadic and Nontornadic Supercells During the 24-25 May 2011 Outbreak

April 19th, 2024

3:30 pm

NWC 1350

Abstract: Supercells tend to produce the strongest and longest-lived tornadoes, causing insurmountable destruction of property, loss of life, and impacts to society. To mitigate these impacts, understanding the formation of supercell tornadoes is crucial. There are many studies that assess the predictability of tornado formation and failure across various environments. Within this subset of studies, there is both observational and simulation work that relates dual-polarimetric radar signatures with tornado formation and intensity. However, such studies fail to address how both tornado failure and genesis occur within the same environment, and if this distinction is predictable using dual-polarimetric radar signatures. With this in mind, this project looks dual-polarimetric radar signatures across the ensemble of supercells that occurred during the 24–25 May 2011 tornado outbreak. This event provides a suite of storms that produced strong, long-lived tornadoes; weaker, shorter-lived
tornadoes; and storms that produced no tornado at all. The following dual-polarimetric radar signatures for each supercell were analyzed at each time step: differential reflectivity (ZDR) column area and height, ZDR arc area and centroid, and specific differential phase (KDP) foot area and centroid. In addition to an analysis of the dual-polarimetric radar signatures, the impact of mesoscale heterogeneities in the near-storm environment will be assessed using the Oklahoma Mesonet and European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) data. Preliminary analyses show that, while the ZDR column heights across the suite of supercells are similar, supercells that produced the strongest tornadoes have larger ZDR column areas than the nontornadic supercell. Furthermore, in the supercell that produced the El Reno tornado, the distance between the KDP foot and ZDR arc is larger compared to the nontornadic supercell. The KDP foot also shifts northward within the
supercell during the El Reno tornado, which is consistent with past findings for tornadic supercells. The comparison of dual-polarimetric radar signatures in supercells in the same environment is directly applicable to forecasting. Potential distinctions in dual-polarimetric radar signatures across nontornadic, weakly tornadic, and strongly tornadic supercells can help increase warning lead times in addition to providing extra forecast information for operational meteorologists.