Regional Variations in the Meteorological and Societal Implications of Storms Producing Significant Tornadoes

Recent climatological studies identified regions of higher tornado occurrence outside of the Plains states, but these studies do not show that statistically significant differences exist separating various regions. Preliminary work using six years of data (2007-2012) suggests that significant differences in tornadic storm modes exist between the Southern and Northern Plains, where supercells are more prevalent, and the Southeast and Midwest, where higher proportions of tornadoes are associated with mesoscale or quasi-linear convective systems (MCS/QLCSs). Dual-polarization upgrades to the WSR-88D network between 2011 and 2013 now allow for investigation into the dual-pol radar properties of a subset of storms producing significant tornadoes to better identify variability between regions and account for potential biases in storm surveys and Storm Data. Additional objectives include investigating societal and forecasting implications of these differences, including their potential effect on tornado warning-lead times, path length and width, and loss of life and property.

Approximately 1350 significant (EF2+) tornadoes identified over nine years in Storm Data from February 2007- January 2016 are matched with their parent storms using archived WSR-88D radar data. Each storm’s structure is classified into one of three groups: discrete supercell, QLCS/MCS, and other. Supercells and QLCS/MCSs are further subdivided into non-mergers and mergers. Each storm’s structure (e.g. high-precipitation supercell, trailing-stratiform MCS) is identified along with the dual-pol properties of each storm sampled after the WSR-88D upgrades to determine similarities and differences across each region of the United States. Tornado warning lead times and statistics will also be analyzed if time permits to identify variations in lead times with respect to region and/or storm type and structure. The results of this study will help meteorologists and core partners of the weather enterprise to better understand the threats and warning capabilities specific storm modes pose in their respective regions, enhancing outreach initiatives and messaging to the general public.