Tropical Cyclone Supercell Response to the Coast Using a Climatology of Radar-Derived Azimuthal Shear

Supercells in landfalling tropical cyclones (TCs) often produce tornadoes that can cause fatalities and extensive damage. In previous studies, many tornadoes have been shown to form <50 km from the coast, and their parent storms may also intensify as they cross the coastal boundary. This study uses WSR-88D observations of TC tornadic mesocyclones from 2011 to 2018 to examine changes in their low-level rotation upon moving onshore. We will show that radar-derived azimuthal shear tends to increase in storms that cross the coastal boundary. Similar intensification trends are also found in radar-derived (supercell) storm-scale divergence, such that storm-scale convergence increases as storms move onshore. It is likely changes in the near-coast vertical wind shear and/or near-shore convergence helps explain supercell intensification, which is important to consider particularly in operational settings.