WRAL WeatherCenter Blog

Ice of another kind

Posted March 4

A 2-pound hailstone fell in South Dakota during a July 2010 storm.

— You've probably never heard of Vivian, S.D., but on July 23, 2010, that sleepy little town made headlines around the world.

Severe thunderstorms rolled through that hot summer afternoon, depositing large hail, with one hailstone reaching mammoth proportions. It only takes hail reaching 1 inch in diameter to be considered severe, but one stone fell that afternoon reaching 8 inches in diameter, weighing 1.93 pounds with a circumference of 18.62 inches.

As it turns out, this was record breaking, surpassing the previous record hailstone, which fell in Aurora, Neb., in 2003.

That 2010 storm in Vivian must have had some terrific updrafts that sustained the hail aloft long enough to form something that large. Since a strong updraft is needed to support such weight, hail is typically produced by very strong thunderstorms. In fact, to support a grapefruit-sized stone, a speed of approximately 100 mph is needed.

Hail is a threat to life and property and has been responsible for millions of dollars worth of damage in North Carolina. Fortunately for North Carolina, we don't see hailstones that large and likely never will. The ingredients for hail to form on such a grand scale don't come together all that frequently across the Plains and never occur here.

Yes, we do have our share of hailstorms. The season for hail in North Carolina runs from March through July, with the peak occurring in May. In the month of May, we have a good combination of a low freezing level in the atmosphere and good heating at the surface, which helps hail to form. We typically see dime-, nickel- and penny-sized hail, which aren't considered severe.

When we see hail reach the size of quarters or an inch in diameter, then we typically have a severe thunderstorm warning in progress. There have been many occasions where tennis ball-sized hail and baseball-sized hail have been reported across our state, but those instances, thankfully, are not that common.

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