Research News

'Gargantuan' hail in Argentina may have smashed world record

Hailstones were so large scientists suggest a new category to describe them

A supercell thunderstorm pelted a city center in Argentina with hailstones so large that scientists have suggested a new category to describe them -- gargantuan hail.

National Science Foundation-funded researchers investigating the 2018 storm found one hailstone that measured between 7.4 and 9.3 inches in diameter, potentially setting a new world record. The current record belongs to a hailstone that measured 8 inches in diameter, or about the size of a volleyball, that fell near Vivian, South Dakota.

"It's incredible," said Matthew Kumjian, an atmospheric scientist at Penn State. "This is the extreme upper end of what you'd expect from hail."

The researchers have proposed that hail larger than 6 inches should be classified as gargantuan; they say that more awareness of such events, while rare, could help piece together a better understanding of dangerous storms.

"Anything larger than about a quarter in size can start putting dents in your car," Kumjian said. "In some rare cases, 6-inch hail has actually gone through roofs and multiple floors in houses. We'd like to help mitigate the impacts on life and property, to anticipate these kinds of events."

The storm in heavily populated Villa Carlos Paz, Argentina, offered scientists a rare opportunity to study a well-documented case of gargantuan hail. As the storm unfolded, residents took to social media, posting pictures and videos.

Researchers followed up on the accounts a year later, interviewing witnesses, visiting sites where damage occurred, collecting photogrammetric data and analyzing radar observations. Using photogrammetry -- taking measurements from photographs -- and video evidence, the scientists estimated that one hailstone may have set a world record.

The scientists reported their findings in the Bulletin of the American Meteorological Society.

"Such a well-observed case is an important step forward in understanding environments and storms that produce gargantuan hail, and ultimately how to anticipate and detect such extreme events," Kumjian said.