WSR-88D analysis of tornadic and nontornadic deep convection in landfalling tropical cyclone rainbands

Landfalling tropical cyclones (TCs) commonly spawn tornadoes along coastal regions. In the United States, as much as 10% of the lives lost during TCs are a result of the tornadoes spawned in these storms. While these areas of deep convection resemble their supercell counterparts of the Great Plains, there are differences in size, longevity, and intensity. These issues create problems for forecasters who need to warn the public of their danger. Prediction of these tornadic events can be difficult when determining which convective cells will become tornadic out of the hundreds that move onshore. If common features for the tornadic and nontornadic cells can be determined while the cells are still offshore, then a greater lead time for forecasters can be accomplished and earlier warning can be provided to the public. The goal of this study is to identify distinguishable radar-derived characteristics of tornadic convection prior to tornadogenesis within the rainbands of landfalling TCs.

This study will utilize NEXRAD Level-II data obtained from the Tallahassee (TLH) NWS WSR-88D radar for the 15-16 of September 2004 as Hurricane Ivan's outer rainbands made landfall along the Gulf Coast. GR2Analyst software will be used to complete the analysis of this radar data. Numerous tornadic and nontornadic cells will be tracked prior to and as they move onshore. Several radar products such as base reflectivity, base velocity, spectral width, echo tops, and vertically integrated liquid will be tracked for each convective cell. A synopsis of our results and their comparison with previous studies will be presented at the conference.