'Gargantuan' Hailstone From Argentina May Be World's Biggest

The researchers of a new study noted a massive hailstone from Argentina may have set a world record, snatching the one by a hailstone from South Dakota. The event in Argentina showed that such high-impact events can happen in various parts of the world.

On Feb. 8, 2018, a supercell thunderstorm that hit the city of Villa Carloz Paz in Córdoba Province, Argentina, produced massive hailstones. In fact, the hailstones were so large that scientists proposed they should be described as "gargantuan hail."

The hail storm was well documented, with the residents posting photos and videos of the event on social media.

Upon visiting the site a year later, the researchers observed three "noteworthy" hailstones that the residents found.

One of them is estimated to measure between 7.4 and 9.3 inches based on the photographs, which, according to researchers, is "close to or exceeds" the current world record holder for maximum dimension. This means it is possible the hailstone from Argentina has snatched the world record of the 2010 hailstone from Vivan, South Dakota, which measured 8 inches across and weighed 1 pound, 15 ounces.

"It's incredible," study co-author Matthew Kumjian said in the press release from Penn State. "This is the extreme upper end of what you'd expect from hail."

Hailstones form when thunderstorm updrafts carry raindrops into extremely cold areas of the atmosphere where they freeze. They then get bigger when they collide with other liquid water drops that freeze onto the hailstone's surface. When the thunderstorm's updraft can no longer support the weight of the stone, whether because the updraft has weakened or because the hail has become large, the hail falls to the ground.

Study co-author and graduate student Rachel Gutierrez noted the larger size of the hailstones could have something to do with how fast the storm's updraft is spinning, but the exact relationship between these two factors are still largely unknown.

According to the researchers, hail that is larger than six inches should be classified as "gargantuan."

Although such events are rare, when they do happen and the hailstones fall at significant speeds, they are large enough to inflict damage on properties and even harm people and livestock. As such, it is important to understand these rare events better.

"We'd like to help mitigate the impacts on life and property, to help anticipate these kinds of events," Kumjian said.

According to Gutierrez, there is "not a lot of data" from such storms outside the U.S., but the event in Argentina shows that they can happen in different parts of the world.

"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," the researchers wrote in their study published in the Bulletin of the American Meteorological Society.