This metal poster, bearing the likeness of a Smithville, Mississippi child who died of bone cancer in 1998, flew more than 50 miles to Russellville, Alabama, where it was recovered, and eventually reunited with the child's parents through Patty Bullion's Facebook page.
When a series of EF5 tornadoes, the most powerful on the scale, hit Alabama and areas of surrounding states, houses were torn apart, their contents scattered by the winds. Almost all the photographs, diplomas, magazines, and objects were lost, but a few were found thanks to a collective effort organized through a Facebook page created by Patty Bullion, a resident of Lester, Alabama, population 111.
The page she made, called "Pictures and Documents found after the April 27, 2011 Tornadoes," began with items she found in her own yard, but expanded as more people heard about the page and contributed belongings they'd found. Within a year, more than 100,000 people had "liked" the page and 1,700 items were returned to their owners through the simple matchmaking of the project.
This attracted the attention of John Knox, a weather and climate scientist at the University of Georgia. He'd studied meteorology at the University of Wisconsin-Madison, where Charles Anderson had done a pathbreaking study on the debris fallout from the Barneveld Wisconsin tornado, and was familiar with the work of John Snow at the University of Oklahoma, who extended the study of debris through aggregating historical newspaper accounts. Both efforts suffered from the same defect: it was hard to build a large enough dataset to offset the low precision of many reports. In the past, it was simply logistically, practically difficult to find a lot of people who had both lost and found items.
That is, until Bullion created her Facebook page, and through word-of-mouth, people across the region made it into the hub for returning items to their owners. Knox knew a novel dataset when he saw one, and he contacted Bullion, who allowed his students to access her Facebook account. They painstakingly took the postings and turned them into structured data that they could study. Out of respect for tornado victims, Knox decided against contacting people who'd lost items, sacrificing some data and precision. He called his decision-making process "data mining with a heart."
With that limitation in place, they set about figuring out which objects had defined beginning and endpoints. They were aided by the fact that many of the towns in which people lost and found items were geographically small, so they could circumscribe both poles of the trajectory easily. Still, they had to throw out 800 objects for which they could not ascertain decent geo-data.
What remained was the most impressive database of tornado debris takeoff and landing points ever assembled. The largest previous dataset (Snow's) had 163 objects drawn from decades of historical accounts. This was 934 objects from a single tornado outbreak.
This chart shows the distance different types of objects traveled during the storms. A light object is defined as weighing less than one pound; a heavy object is over one pound. No light or heavy object traveled more than 90 miles.
In tornado studies, new work with dual-pol radar has been showing that debris gets very, very high in these storms. Riding 100 mile-per-hour updrafts within a tornado and slower but still strong updrafts within their parent thunderstorms means that light objects and paper are ending up miles in the air.
"There is a real sense [debris] is going up at least six kilometers into the storm," Knox said. "What I'm hearing from meteorologists who are using the dual-pol radar technology is that they are seeing debris at 20,000 feet and sometimes more."
Which would explain how, in Knox's study, some pieces of paper debris ended up more than 200 miles away. Their hypothesis, as noted, is that the debris shoots up the tornadoes, where much of it is held aloft for around 100 miles, and that tends to fall slightly to the left of the tornado track, as the storms are pushed north by winds from the south. But some debris seems to end up riding the updrafts up and right out of the top of the thunderstorms. Up there, it would meet with the jetstream, which would push the debris a long way and land it farther eastward than the tornado track or other debris.
"Trajectories based on the takeoff and landing points of lost-and-found objects revealed that most debris was deposited 10 degrees to the left of the average tornado track vector," Knox and his co-authors wrote. "However, objects that traveled the longest distance were found approximately 5 degrees to the right of the average tornado track vector."
That would explain the results we see below, where some debris has shifted over the paths of other objects in an eastward direction. "That had not been seen in any previous study, but it makes a lot of sense. Once you see it, you say, 'Oh, that's what happened,'" Knox told me.