Reducing NWS Tornado FAR – An Examination of Near-Storm Environmental Parameters in Tornado-Warned Thunderstorms across the Midwest and Ohio Valley

The National Weather Service's mission is to protect life and property through the issuance of critical weather warnings. Recent assessments from high-impact events, such as the EF-5 Joplin, Missouri tornado suggest that the general public does not always respond to these life-saving warnings due to complacency brought on by a high false alarm rate (FAR). As a result, this study was undertaken to examine and better understand tornadic near-storm environments in an effort to reduce NWS tornado warning FAR across the Ohio Valley, an area highly susceptible to multi-mode tornadic convection.

A large sample of tornado warnings dating back to 2009 was collected from several NWS offices in the Midwest and Ohio Valley, along with corresponding sectorized Storm Prediction Center (SPC) mesoanalysis data. If a tornado occurred within 2 hours and 100 miles of an issued warning, then the environment was classified as a tornado-producing environment. Using mosaicked NWS Doppler base reflectivity data, these tornado-warned storms were then classified into either a quasi-linear convective system (QLCS) mode or a discrete cell. Statistical analyses were performed on over a dozen thermodynamic and kinematic environmental parameters. The results of these tornadic versus non-tornadic environments, including detailed comparisons of QLCS-type and supercell environments within the Ohio Valley are discussed. The findings from this study are then compared with existing research on tornadic environments.