Tornadoes pose perhaps their greatest risk to life and limb when they threaten large outdoor crowds in festivals, stadiums and other venues. Nontornadic but unusually severe supercells and derechos are of considerably heightened concern when they threaten these same outdoor venues with extremes in hail, winds, flooding rains, and virtually continuous cloud-to-ground lightning. This article is intended to increase awareness of this very real threat by documenting severe weather hazard for large event venues using both historical examples and available risk assessments. We also suggest a cooperative, multidisciplinary approach designed to minimize the potential catastrophic threat to human life.

Significant tornadoes have passed close to such gatherings on a few occasions, including a crowded dog-racing track in West Memphis, AR, on 14 December 1987. A nontornadic supercell hit a riverside festival in Ft. Worth in 1995, catching over 10,000 people outdoors and injuring many of them with hail larger than baseballs and taking the lives of nearly 20 people. More recently, tornadoes have struck large stadiums that were serendipitously empty, including the football stadium for the NFL Tennessee Titans and the basketball arena for the NBA Utah Jazz. There exists a very real threat of massive death tolls if a stadium, race track or fairground is hit by a violent tornado during a concert, festival or sporting event -- even with a warning in effect. Under these circumstances, many spectators may not know about the warning, and even if they do, evacuation problems and resulting panic may produce casualties with or without a direct severe storm strike. In fact, we suggest that this is not a threat that may occur but one that will occur unless we take proactive measures to prevent a catastrophic loss of life and massive numbers of injuries.

We are suggesting a national multidisciplinary meeting to address this threat directly. The structure of that meeting and its hopeful result will be discussed. We also suggest that the integrated warning system (IWS) partnership, involving the National Weather Service (NWS), news media, and emergency managers and spotters, should collaborate and coordinate with individual venue operators to reduce the risk of mass casualties in violent weather.