Radar-observed eyewall tilt and three-dimensional winds of Hurricane Isabel (2003)

Hurricane Isabel made landfall near Drum Inlet, North Carolina at about 1700 UTC 18 September 2003 and was a Category 2 hurricane with a maximum surface wind speed of about 45 ms-1 right before landfall. Five WSR-88D (Weather Surveillance Radar - 1988 Doppler) radars were in the landfall region with the KMHX radar at Morehead City of North Carolina located right inside the hurricane eyewall when the front edge of the hurricane eye reached the coastline. The multiple radar observations provided an opportunity to examine the fine structures of the hurricane eye and eyewalls before and during Isabel's landfall. The three-dimensional structures of Hurricane Isabel was re-constructed from the observations of the full-resolution, full-volume reflectivity scans by the five WSR-88D radars in the landfall region using the Naval Research Laboratory (NRL) Three-dimensional Radar Mosaic System. Three-dimensional winds inside the inner core region were also retrieved from the multiple-radar measurements of Doppler radial velocity using a variational algorithm. In this study, we focus on the relationship between the hurricane eyewall tilt and the three-dimensional winds, especially the vertical wind shear and the variation of tangential wind speed with height. Detailed results and discussions will be presented at the conference.