Composite analysis of environmental conditions favorable for significant tornadoes across eastern Kansas

Predicting significant tornadoes (EF2 or greater) remains a considerable challenge to the operational forecaster. While these significant tornadoes occur with less frequency than weaker ones, they are responsible for a disproportionate amount of the damage, injuries and fatalities associated with this weather phenomenon. Thus, improvement in forecasts for these tornadoes has the potential to provide valuable assistance to first responders, emergency management, media outlets and the general public.

To help forecasters identify patterns likely to produce significant tornadoes across eastern Kansas, tornadoes were categorized and composites of their environments were produced based on those categories. Significant (EF2 or greater) tornadoes from 1979 to 2007 were identified, and subjective surface analyses for each of the significant tornadoes were done. Based on the surface analyses, tornadoes were classified into two categories: tornadoes occurring near a mesoscale surface boundary, and those taking place without any discernable surface boundary present, often in the warm sector of a surface cyclone. North American Regional Reanalysis data for the hour proceeding the time of the tornado were used to create a composite for each category. Composites were also constructed based on the seasons in which significant tornadoes have been recorded. The resolution of the reanalysis data allows an examination the convective environment on a meso-beta scale, including vertical wind shear and convective available potential energy. Results comparing and contrasting the different environments will be presented.