On Some Issues of United States Tornado Climatology

Abstract

A continuing problem in dealing with climatology data concerning tornadoes in the United States is the validity of the quantitative information contained in the various available data bases. Two aspects of tornado data are discussed: the F-scale rating and the occurrence of very long path length events. The argument is advanced that the F-scale is more properly thought of as a damage scale than as an intensity scale. Failing to recognize this leads to confusion and controversy regarding the F-scale ratings assigned to events in the data base. Changing perceptions of tornadoes have led to some questions concerning the actual frequency of very long path lengths, on the order of 100 statute miles (160.9 km) or more. Evidence is presented that at least some of the events classified as having long tracks are most likely the result of misinterpreting the results of a series of short-path tornadoes, produced by a single supercell thunderstorm. Some discussion is presented concerning the implications of the problems with the data. Since the climatological record is of both meteorological and societal concern, some alternatives are considered, but no hard conclusions can be drawn without considerable further effort.