9.5 The 24 May 2005 multiple-vortex tornado in southeastern Brazil

Wednesday, 8 November 2006: 11:30 AM
St. Louis AB (Adam's Mark Hotel)
Ernani L. Nascimento, Universidade Federal de Santa Maria, Santa Maria, Brazil; and I. P. V. O. Marcelino

During the late afternoon hours of 24 May 2005 a severe weather outbreak occurred east of a migratory baroclinic system in the state of São Paulo, in southeastern Brazil. Heavy rainfall, significant floods and damaging winds were reported in several locations in São Paulo state that afternoon, with some severe weather reports associated with isolated thunderstorms developing ahead of an advancing surface cold front. One isolated storm, displaying supercell characteristics, produced a significant multiple-vortex tornado on the outskirts of the city of Indaiatuba, and was captured on video by a local highway monitoring system. Visual characteristics of this rare significant tornado in the Southern Hemisphere are described, as well as some results from the damage assessment conducted for this event. A brief analysis of the severe weather environment in which the tornadic supercell developed also is presented. The tornado intensity reached F3 in the Fujita scale, and the atmospheric environment conducive to the thunderstorm development shared some characteristics similar to those often observed in the Central Plains of the United States during severe weather season.
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