Role of Unusual MCS Morphology in the Table Rock Lake Duck Boat Tragedy and its Implications for Messaging to Vulnerable User Groups

On July 19th, 2018 a violent derecho swept across Table Rock Lake in southwest Missouri, sinking a tourist duck boat and killing 17 people. The event is an example of how the intersection between a significant weather event, exposed user groups and human decision making can complicate the warning message and warning response. The somewhat atypical morphology of the derecho and its extreme nature will be discussed. In addition, there were several aspects in the evolution of this event that enhanced the threat associated with these storms. The violent winds arrived well ahead of the convective towers, and the associated lightning, often leaving exposed groups unaware of the approaching threat until the high winds arrived. In addition, the duration of the extreme winds, often 20-35 minutes, was unusually long, which enhanced the threat and hampered immediate response.

The societal impacts associated with the derecho will be also presented. The derecho impacted an area with numerous campgrounds and large recreational lakes, which included a large transient and exposed population. Strategies for communicating threats to these populations, and the local infrastructure that supports them, will be addressed. The use of arrival times at key recreation sites (State Parks, marinas etc.) in National Weather Service warnings may prove especially beneficial to such groups. In addition, lessons learned about communicating unusual aspects of an event such as this, including the anomalously rapid storm motion and the long duration of the violent winds, may help exposed users better understand the danger associated with similar events.