The earliest documented tornado in the Americas

Abstract

We discuss a meteorological phenomenon that occurred in the Basin of Mexico in August 1521. The only known description appears in Book XII of the Florentine Codex, which is an account of the Spanish conquest of Mexico written in Nahuatl in the mid-sixteenthcentury. According to it, just before the fall of Mexico-Tenochtitlan a heavy storm accompanied by a whirlwind struck the basin. The whirlwind hovered for a while above Tlatelolco, Tenochtitlan's twin city, before moving to the lake where it disappeared. Analyzing the account in the context of Nahua culture and contrasting it with contemporary European descriptions of tornadoes and waterspoutsshows that the described phenomenon was a tornado. Since this event predates the Cambridge tornado of 1680 (Mather 1856; Ludlum 1970),the tornado of Tlatelolco represents the earliest tornado on record in the Americas. Documentary sources show that severe storms and tornadoes have occurred under the various climatological conditions that have prevailed in the Basin of Mexico throughout the last five centuries (Velasco Fuentes 2010, unpublished manuscript). This is particularly significant because this basin is now the seat of one of the most populous cities in the world. Even a weak tornado could represent a serious threat to life and property in such a densely populated area. © 2010 American Meteorological Society.