An Increase in the Number of Tornado Reports in Brazil

Abstract

his paper presents the development of tornado reports in Brazil since the middle of the twentieth century, both for the country as a whole and for the five regions of Brazil: the south, southeast, central-west, northeast, and north. No official tornado registry exists in Brazil so the reports come from various sources. Most of the tornadoes reported are from the south and southeast regions. The low number of reports for the central-west regions suggests, in view of the literature on intense storms and mesoscale convective complexes, that most tornadoes cases go unreported. The increase in tornado reports is compared to the evolution of population density and communications, with the latter represented by the evolution of local television stations and the popularization of the Internet. One particular event is a new Web site for volunteer tornado reports, which has completely changed the trends of tornado reports. Another possible cause for an increase in the number of tornado reports in the south and southern regions could be a shift in climate variability in this region in the 1970s, which has been reported by several authors. However, the increase in rainfall and extreme events reported by these studies point to an increase of as much as 40%, which is not compatible with the observed tenfold increase in tornado reports.