Content area
Full Text
1. Introduction
On 23 November 1981, a strong cold front swept across the United Kingdom, producing an unprecedented 104 reports of tornadoes (Fig. 1). Called Britain’s greatest tornado outbreak (Rowe and Meaden 1985), this event had many more tornadoes than the next largest event just a month earlier on 20 October 1981, which spawned only 29 tornadoes (Turner et al. 1986; Rowe 2016). For comparison, even modest outbreaks by U.S. standards are relatively uncommon in the United Kingdom. Specifically, over 90% of U.K. tornado days between 1980 and 2012 had fewer than eight tornadoes (Fig. 14 in Mulder and Schultz 2015). The November 1981 outbreak is so exceptional that it distorts the historical record and climatologies of tornadoes in the United Kingdom and Europe. For example, in the U.K. tornado climatology by Mulder and Schultz (2015), several figures had to be plotted with the outbreak excluded (e.g., their Figs. 5–7, 9, 12, and 13), and, in their review of tornadoes across Europe, Antonescu et al. (2016) found that the large number of reports produced a bias in their synthesized results and capped the total number of reports from this outbreak at 58. Given the large number of reports distorting the climatologies and that a scientific study of this event has not been performed in nearly 35 years, we believe that the time is right to reexamine this event.
The locations of these 104 reports (Fig. 1) come from the Tornado and Storm Research Organisation (TORRO). TORRO is a U.K.-based not-for-profit organization responsible for collecting tornado reports from the media, from over 350 observers in the United Kingdom, and from the public through TORRO’s website (http://www.torro.org.uk) (e.g., Elsom et al. 2001; Doe 2016). Of the 104 reports on 23 November 1981, 35 came from media reports, 30 came from the public after a call for reports on Anglia Television, and 39 were the result of TORRO’s appeal in local newspapers (Rowe 1985). The challenges of severe-weather event verification can be immense, even when events are well observed by expert meteorologists (Speheger et al. 2002; Trapp et al. 2006). The challenges are compounded when reports are collected well after the event from primarily nonmeteorologists, as was the case in this event.
The first tornadoes of the day...