Isabel, a category 2 hurricane, made landfall on the outer banks of North Carolina near 17 UTC on 18 September 2003. The center of Isabel entered Doppler range of the Morehead City WSR-88D (KMHX) after 11 UTC 18 September 2003. After Isabel made landfall, it was continuously monitored by KMHX, KRAX (WSR-88D at Raleigh/Durham, NC) and KAKO (WSR-88D at Wakefield, VA) for the next 10 hours. This unique distribution of WSR-88Ds allows not only single Doppler radar analysis but also dual-Doppler analysis of the inner core region of Isabel.

The purpose of this paper is to document Isabel’s inner core structure during an 18 hour period before and after it made landfall. The circulation centers of Isabel during this period will be deduced and compared with the NHC operational fixes. We will apply the ground-based velocity track display (GBVTD) technique to the WSR-88D data in six-minute interval to document the three-dimensional structure of Isabel’s inner core region. This is a unique dataset to examine the evolution of inner core structure before and after Isabel’s landfall during its decaying stage. We will show the evolution of both the axisymmetric and asymmetric structure of Isabel in the conference.