Comparison of Tornadic and Nontornadic Convective Cells in Hurricane Harvey

The 2017 tropical cyclone season reaffirmed the particular forecast challenge posed by tornadoes associated with convection in the rainbands of landfalling tropical cyclones. Hurricane Harvey, in particular, was a prolific tornado producer, resulting in 52 tornadoes across six states. The multifaceted threats of tropical cyclones often limit resources available to forecasters in the warning decision process, and the result is often a relatively high false alarm ratio. We hypothesize that better understanding of the differences between the attributes of tornadic and nontornadic convective cells and their environments in landfalling tropical cyclones will lead to more efficient discrimination of potentially tornadic cells and improved warning skill.

This study presents a comparison of attributes and the near-cell environments of warned tornadic (hits) and nontornadic (false alarm) cells in Hurricane Harvey. Comparisons of reflectivity, Doppler, and polarimetric radar attributes in addition to lightning flash density will be presented. Near-cell environments obtained from high-resolution model analyses will also be compared between hits and false alarms, with an emphasis on low-level kinematic and thermodynamic profiles. Finally, results from Harvey will be compared with those obtained from other landfalling tropical cyclones from the 2017 season.