Investigating Changes in the Precipitation Structure of Tropical Cyclones After Landfall

Landfalling tropical cyclones (TC) are associated with extreme wind and flooding that present hazards to those living near the impact zone and inland. Prior work has shown that TC winds are most extreme upon landfall and decrease exponentially thereafter. Additionally, a series of modeling suggests that TCs at landfall have symmetry and shortly after are significantly weaker, lack an eyewall, and have an increase in asymmetry. However, there is an incomplete understanding of how the precipitation structure decays following TC landfall utilizing observations. Prior work also suggests that the variation in environmental wind with height (i.e., vertical wind shear) strongly impacts the strength, intensity, and azimuthal location of asymmetries of hurricanes, including potentially after landfall, but its influence has yet to be largely tested over land.

To test these hypotheses, we investigate how the precipitation structure decays following landfall using Next Generation Weather Radar (NEXRAD) radar data from a sample of 28 landfalling TCs. Preliminary results show that the precipitation structure decays most rapidly in the inner core following landfall. Precipitation structure additionally becomes more asymmetric towards the down shear sector of the TC as time increases after landfall.