February 10, 2018
A violent hailstorm hit Cordoba, Argentina on Thursday afternoon, February 8, 2018. The storm started around 16:30 local time with small hailstones that didn’t cause much damage. However, hailstones grew bigger over the next 20 minutes and eventually reached up to 20 cm (7 inches) and more.
Although it’s still not officially confirmed, the largest hailstone had a diameter of 23 cm (9 inches).
Currently, the largest hailstone officially confirmed fell on Vivian, South Dakota, US on July 23, 2010. It measured 20.32 cm (8.0 inches) in diameter, 46.99 cm (18.5 inches) in circumference, and weighed in 0.878 kg (1.9375 pounds).
Hail can reach this size only if thunderstorm updrafts are strong enough to keep it suspended in the air. That would require vertical winds exceeding 193 km/h (120 mph), Capital Weather Gang meteorologists explained.
“As layers of ice glaze onto the growing stone, erratic winds high in the sky can carry it into dry regions. When that happens, the outside of the stone freezes faster than the inside. This has been shown to produce bizarre protrusions, which grow with each successive pass through the cloud. Once the stone becomes too heavy, it falls out of the cloud, sometimes faster than a major league baseball pitch,” CWG’s Matthew Cappucci explained.
“In events like this, each hailstone contains so much water that fewer stones end up forming. That’s why there’s a large gap between where they strike — sometimes landing 20 or more feet [6+ meters] apart.”