Database Co-produced by UMD Undergrad Is First to Document Tornadoes Worldwide
Archive Captures Records on 100,000 Twisters, From U.S. Plains to Eastern Hemisphere
By John Tucker
The outflow from Tropical Storm Toraji spawned tornadoes that caused injuries and property damage in Japan in September 2013. A UMD undergraduate helped create a global database of tornadoes that could spur greater understanding of how twisters form in places where they're less prevalent than the U.S. Great Plains' so-called Tornado Alley.
Photo by NASA
The world’s oldest documented tornado likely occurred in Sardinia in 200 AD. What’s probably the northernmost recorded twister hit Norway in 2005, a rare occurrence in the Arctic Circle. In 2001, one that ripped through the University of Maryland campus killed two students.
Those are among the facts detailed in a first-of-its-kind archive built by a research team co-led by UMD undergraduate Malcolm Maas ’25. It offers a historical record of more than 100,000 tornadoes that spun through all 50 states and every continent but Antarctica.
Until now, individual attempts to document twisters outside of the United States have been inconsistent, sometimes even contradicting each other. Maas’ archive streamlines data cultivated from all corners of the globe. The project was detailed in a recent paper published in the Bulletin of the American Meteorological Society, with Maas serving as lead author.
Malcom Maas '25
“The dataset is a first step toward having unified documentation of tornadoes everywhere, with scientific findings transferable from one country to another,” said Maas, a double-degree student in physics and atmospheric and oceanic science.
The project’s website, tornadoarchive.com, features maps and filters to visualize the data, measuring each tornado’s path, strength and resulting deaths. The research team built the site as a hub for climatologists and other scientists, as well as laymen interested in tornado history.
“A lot of tornado research has been focused on the U.S., but they occur in other parts of the world, and we wanted to make it easy,” said Timothy Supinie, a meteorologist for the Storm Prediction Center in Norman, Okla., who coauthored the paper.
Maas developed interest in severe weather in elementary school, when snowstorms canceled classes. Awed by thunderstorms lashing his house in Bethesda, Md., he became jealous of storm chasers. In 2021, as a high school junior, he connected on Twitter with tornado enthusiasts across the country, most of whom were graduate students. An existing U.S. tornado history website had fizzled, and Maas and his acquaintances saw an opportunity to build their own.
Maas, who had programming experience, offered to help develop a website and eventually started managing data collection. For two years he culled tornado tallies from foreign governments and research organizations. When he faced hurdles, mainly in less developed countries, he hunted down individual scientists and doctoral students.
The hodgepodge of data arrived in different formats, measurements and languages, making integration laborious. Nevertheless, the project’s website raked in 160,000 page views in its first year.
Maas arrived at UMD as a freshman in the Honors College, and soon helped install a campus weather station that uses sensors to gather data for windfall, rainfall and windspeed. He built user-friendly graphs to visualize the data, which are displayed on the UMD Weather website.
In 2023, when the Maryland Department of Emergency Management and UMD erected a 30-foot tower in Howard County to speed early warnings of dangerous weather, officials asked Maas to adapt his tools to help display their own data, helping ensure the safety of Marylanders.
“Malcolm is doing the research at a level you’d expect from a second- or third-year graduate student,” said Jonathan Poterjoy, a UMD associate professor of atmospheric and oceanic science and Maas’ research adviser.
To quantify U.S. tornadoes since 1950 for their archive, Maas and his collaborators relied on the National Centers for Environmental Information. For earlier twisters, they turned to a print volume written by meteorologist Thomas Grazulis, who cited tornadoes as early as 1680, largely through newspaper clips referencing single towns, some of which no longer exist. The research team digitized the information and added geographic coordinates.
The United States is the runaway leader in recorded tornado occurrences, followed by Russia, Canada and Germany, according to the archive.
The repository is far from complete, partially because certain datasets were inaccessible to Maas’ team. In addition, many tornadoes have gone unreported while some clusters were misidentified, mainly by journalists, as individual storms. Conversely, many windstorms have been misclassified as tornadoes.
Tornado-related fatalities have also been undercounted, considering, for example, that enslaved Americans weren’t always included in the record. Likewise, though Oklahoma is likely North America’s tornado hotspot, Maas suspects Kansas led in the count in the 19th century because most of the Sooner state’s storms were seen only by the state’s Native American population.
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