Examining the pre-landfall environment of Mesovortices within a hurricane Bonnie (1998) Outer Rainband

Outer rainbands of Hurricanes Bonnie and Earl (1998) spawned tornadoes across eastern North Carolina and the Florida Panhandle, respectively. Prior to the tornadoes, Doppler radar observations revealed numerous shallow circulations upstream, embedded within rainbands originating offshore. While meteorological observations have been collected and analyzed in close proximity to Tropical Cyclone (TC) tornadoes over land, data from the marine environment where such features often commence are rare. Fortunately, recent airborne experiments conducted by the Hurricane Research Division (HRD) sampled the incipient maritime environment associated with Bonnie and Earl. Dropsonde data collected during these NOAA reconnaissance flights will be exploited to diagnose the vertical profiles favorable for the generation and maintenance of the tropical mesovortices. WSR-88D radar imagery and nearby rawinsonde data will be used to document the downstream mesoscale environments and life cycles of the circulation families as they advect onshore. A companion paper (Dodge et al.) will examine the three dimensional structure of the mesocyclones using dual-Doppler analyses constructed from the WSR-88D and airborne Doppler data sets.