TORNADO DEBRIS CHARACTERISTICS AND TRAJECTORIES DURING THE 27 APRIL 2011 SUPER OUTBREAK AS DETERMINED USING SOCIAL MEDIA DATA

Using publicly available information gleaned from over 1700 found-and-returned objects on the “Pictures and Documents found after the 27 April 2011 Tornadoes” Facebook page, the authors have created a database of 934 objects lofted by at least 15 different tornadoes during the 27 April 2011 Super Outbreak in the southeast United States. Analysis of the takeoff and landing points of these objects using GIS and high-resolution numerical trajectory modeling techniques extends previous work on this subject that used less specific information for much smaller sets of tracked tornado debris. It was found that objects traveled as far as 353 km, exceeding the previous record for the longest documented tornado debris trajectory. While the majority of debris trajectories were 10° to the left of the average tornado track vector, the longest trajectories exhibited a previously undocumented tendency toward the right of the average tornado track vector. Based on results from a high-resolution trajectory model, a relationship between this tendency and the altitude of lofting of debris is hypothesized, with the debris reaching the highest altitudes taking the rightmost trajectories. The paper concludes with a discussion of the pros and cons of using social media information for meteorological research.