An Assessment of the Climatology of Florida Hurricane-Induced Tornadoes (HITs): Technology versus Meteorology

Abstract

he placement of operational Doppler radar at National Weather Service offices in Florida in 1994 and 1995 has produced a distinct climatological discontinuity in archived records of hurricane-induced tornado (HIT) events. During the period of this study (1979?2010), Florida experienced 91 named tropical cyclones (omitting years 1994 and 1995) that produced a total of 300 HITs, as recorded in the NOAA Storm Data climatological publication. The 30 years of records examined for 1979?2010 consisted of 15 years as the pre-Doppler period (1979?93) and 15 years as the Doppler period (1996?2010) and produced an average of 1.92 HITs per tropical cyclone for the pre-Doppler period and 3.85 HITs per tropical cyclone for the Doppler period. Additionally, the HIT statistics were further compiled as the number of HITs per potential HIT day, which yielded values of 0.52 and 1.14, respectively, for the pre-Doppler and Doppler periods. Normalized statistics are based on the total accumulated number of potential HIT days for each period (96 for pre-Doppler and 219 for Doppler). Further, it has been determined that (a) no HITs were recorded in the pre-Doppler period for hurricanes greater than category-2 intensity, ostensibly because of the inability to separate hurricane wind damage from tornado damage, whereas (b) the Doppler period averaged 5.0 and 11.7 HITs per category-3 and category-4 storms, respectively. Finally, this study has clearly documented the magnitude (and effect) of Doppler technology on HITs reported in Florida Storm Data archives. The Doppler era is much more accurate, whereas the pre-Doppler era HIT occurrences are severely underestimated.