Study Tracks Tornado Debris Paths Using Facebook

Tracking the Superoutbreak's Tornado Debris

A team led by Dr. John Knox, Associate Professor at the University of Georgia, pored through hundreds of pictures of debris transported downstream by the outbreak's massive tornadoes to map out start and end points of individual pieces of debris.

"While watching The Weather Channel's live coverage of the outbreak, I noticed reports of debris falling from the sky over parts of the Birmingham metro from the Tuscaloosa tornado," said Dr. Knox, a native of Birmingham.

"I had never seen that level of debris floating in the air.  My brother found prescription bottles in his yard in Birmingham."

What follows on the following pages are some of the incredible photos, images and statistics from this study.   

Let's start with examples of tornado debris found well downstream of their home.

A Sign Found 50 Miles Away

Perhaps one of the most incredible debris recovery stories occurred near Phil Campbell, Ala.

In May 2011, Russellville, Ala. resident Dan Morris (at left in the photo below) found a metal sign in his yard.  

A tribute to Smithville, Miss. band member Lee Frederick, who died from bone cancer in 1998, this sign was hung at the Smithville High School's football stadium.  

The EF5 tornado destroyed 150 homes, 14 businesses and four churches in the town that afternoon. 

A member of the Frederick family identified a photo of the sign posted on Patty Bullion's Facebook page, and the sign was soon returned.

Russellville, Ala. is roughly 50 miles northeast of Smithville, Miss.  The embedded map above is a rough estimate of the debris' origin (red placemark) and final landing spot (blue placemark).  

Next, a windbreaker's amazing ride.

Windbreaker Blown 68 Miles Away

This windbreaker pictured below was found in Elkmont, Ala. and returned to its owner in Hackleburg, Ala., some 68 miles to the southwest.  This was the farthest documented distance in the study of an item weighing over one pound that was returned to its owner. 

The Hackleburg/Phil Campbell, Ala. tornado, the first F/EF5 tornado in the state since April 8, 1998, destroyed 75 percent of the town of Hackleburg, including the high school, many homes and businesses, and a Wrangler plant.

(MORE:  One of 10 Worst U.S. Tornadoes) 

Peak winds were estimated at 210 mph.  This mammoth tornado was on the ground for 132 miles, from Marion County, Ala. to Franklin County, Tenn., claiming 72 lives alone that tragic day.

The embedded map above is a rough estimate of the debris' origin (red placemark) and final landing spot (blue placemark).  

Next, we have the tornado debris that set a new record for documented distance traveled.

Longest Documented Debris Path: 220 miles

The photo shown below took a journey into another state that awful April afternoon in 2011.  

Next in line for the massive EF5 tornado after Hackleburg, the town of Phil Campbell, Ala. was leveled.  

Amidst buildings swept away leaving only the slab foundation, a car wrapped around a debarked tree, and a section of highway's pavement scoured away, the tornado swept up this photo, beginning a 220-mile trip, falling back to the ground in Lenoir City, Tenn. 

Next, the Facebook page that made this all possible.

The Facebook Page That Made This Possible

This study wouldn't have been possible without the efforts of Patty Bullion, a resident of Lester, Ala., and her Facebook page titled "Pictures and Documents found after the April 27, 2011 Tornadoes." 

Bullion created the page shown above (since taken down) within a couple days of the April 27, 2011 outbreak to allow those who found debris to post photos in the hope of reuniting priceless items with their owners.  

In one year, over 1,700 lost items had been returned to their owners, according to the Knox, et al. study. "It was probably the most comprehensive recovery-and-return effort in American weather-disaster history."

"We heard about Patty Bullion's Facebook page and thought that was brilliant," said Dr. Knox. "The question was whether we could use the information, in a sensitive manner, to 'do science.'"

Dr. Knox put out an e-mail to his students to gauge interest in following through with this study. The response: a roomful of students.  

"Hopefully this research shows that we should not limit scientific studies to using traditional forms of data," says Michael Butler (Twitter), meteorologist at The Weather Channel and co-author of the study.

Next, some amazing facts on how many objects were catalogued and how far they flew.

How Far Did the Debris Fly?

The Knox, et al. study examined 934 of the debris reports on Patty Bullion's Facebook page for which a clear origin and landing point could be determined. (Note: There was no effort to contact the tornado victims out of respect for their privacy.)

The graph above shows the distribution of debris travel paths as a function of debris size.  Interestingly, a large number of debris items, mainly paper, were found 125-200 km (roughly 75-125 miles) downstream, which differs from previous studies. "The objects that went the farthest went in a different direction than the rest, a little right of the tornado's path," said Dr. Knox.  

We mentioned the farthest traveling "heavy" debris was the Hackleburg windbreaker on a previous slide. The farthest travel distance for a so-called "light" object (less than one pound, not paper) was 144 km (89 miles).  

In a previous study of tornado debris by Snow et al. (1995), only two objects were documented traveling over 135 miles from 1871-1990. Thanks to the violent tornadoes that day, and the power of social media, the Knox et al. study found 44 items that traveled that distance or greater in just one day.

Finally, let's break out the debris compared to the tornado's EF-rating for some incredible findings.

Lofted Debris vs. Tornado Intensity

Next, the research team examined the distribution of lofted debris categorized by the tornado's EF scale.  

Roughly 74 percent of the recovered debris was from EF5 tornadoes. In fact, 56 percent of the debris in the study was from the Hackleburg-Phil Campbell, Ala. EF5 tornado alone!  

Knox, et al. first points out the study was skewed by the number of violent tornadoes on April 27, 2011, atypical of other studies.

The last question: "Does this research have the potential to improve forecasts?"

"You might be able to integrate our findings with tornado debris signatures (in dual-polarization radar) to give a sense of where debris is raining down," said Dr. Knox.

There's also potential application for hazardous materials. The degree to which tornado debris of various sizes are dispersed downstream may also help emergency planners in the case of a radioactive or biological event.

The full Knox et al. paper can be found here.

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