The need for an improved documentation of severe thunderstorms and tornadoes in South America

The subtropics and mid-latitudes of South America, east of the Andes Mountain Range, have been recognized as prone to severe convective weather for quite some time, including the occasional occurrence of tornadoes. Despite that, there is no institutionalized procedure for a systematic documentation of severe thunderstorms in that part of the world, and the few efforts for documenting severe weather episodes are conducted by individual initiatives with little or no formal support. Because the definition of severe weather is rather arbitrary and based on phenomena produced by thunderstorms at ground level (namely, flash floods, large hail, damaging winds and tornadoes), the availability of a reliable and standardized archive of severe weather reports is fundamental for any quantitative investigation of severe storms. This is particularly crucial in South America, where mesoscale observing systems — including weather radars — are far from adequate, being confined to highly localized regions in the continent.

Building on the North American experience in archiving severe weather reports, we discuss the relevance of maintaining such archives to the study of severe thunderstorms in South America, including the development and testing of techniques to predict severe weather in that continent. We also describe possible ways to start addressing the generation of a severe weather data bank based upon the infra-structure already existent in at least a few countries, such as Brazil.

Finally, we explore some arguments that dispute the general perception that severe convective storms in South America are too rare to justify a serious commitment to this topic by the local atmospheric sciences community at both research and operational environments.