Cloud-to-ground lightning data from the National Lightning Detection Network are examined over the Florida peninsula during the warm seasons of 1989 through 1998. The lightning data are stratified according to the location of the subtropical ridge (i.e., north of Florida, south of Florida, and within Florida) as well as other common flow types. Each day is placed into a flow regime based on radiosonde-derived low-level winds at three stations within the study area. Maps of lightning flash density are generated for each flow regime over hourly, daily (24 h), and nocturnal periods. Results for the 24-h period indicate that complexities in the Florida coastline produce four areas of relatively large flash densities: near Tampa, Fort Myers, West Palm Beach, and Cape Canaveral. Nocturnal lightning is found to occur mostly offshore-related to the Gulf Stream, coastline orientations, the prevailing flow, and land breezes. The location of the subtropical ridge with respect to the Florida peninsula is found to play an important role in the spatial and temporal distribution of lightning. For example, when the large-scale flow is from the southeast, the east coast sea breeze and its associated lightning are relatively weak. However, the west coast sea breeze is strong and remains near the coastline, producing the most lightning near Tampa. Conversely, when the largescale flow is from the southwest, there is relatively little convection along the west coast, but major lightning activity occurs along the east coast.

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Tornadic vortex signatures (TVSs) of 52 tornadoes were identified and analyzed, then characterized as either descending or nondescending. This characterization refers to a known tendency of radar-observed tornadic vortices, namely, that of their initial detection aloft and then of their subsequent descent leading to tornadogenesis. Only 52% of the sampled TVSs descended according to this archetypal model. The remaining 48% were detected first near the ground and grew upward or appeared nearly simultaneously over a several kilometer depth; these represent primary modes of tornado development that have been explained theoretically. The descendingnondescending TVSs were stratified according to attributes of the tornado and TVS. Significantly, tornadoes within quasi-linear convective systems tended to be associated with nondescending TVSs, identification of which provided a mean tornado lead time of 5 min. Two case studies are presented for illustrative purposes. On 1 July 1997 in southern Minnesota, nondescending TVSs and associated tornadogenesis were revealed in the leading edge of a squall line, with a squall linesupercell merger, and later during that day, with the cyclonic bookend vortex of a bow echo. On 22 June 1995 in southern Colorado, a low-topped supercell storm produced a tornado that was associated with a descending TVS.

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