A raging thunderstorm that pounded south-central Nebraska last month ended up leaving a little something extra for residents — and the meteorological record books. The largest hailstone ever recovered in the United States fell in Aurora on June 22, 2003, with a record 7-inch diameter and a circumference of 18.75 inches. The old record for the largest hailstone had a diameter of 5.7 inches, a circumference of 17.5 inches and was found in Coffeyville, Kansas, on September 3, 1970. The Aurora hailstone, however, didn’t break the record for the heaviest. The heaviest hailstones on record weighed in at 2.25 pounds (1.02 kilogram) and were reported to have killed 92 people in Gopalganj, Bangladesh, on the 14 April 1986.

Centuries ago, people in Europe used to ring church bells and fire cannons in order to try to prevent hail. After World War II, cloud seeding was done in order to eliminate the hail threat. To this day, no hail prevention method has proven to work. Hail is common along mountain ranges because mountains force horizontal winds upwards (known as orographic lifting), thereby intensifying the updrafts within thunderstorms and making hail more likely. One of the most notorious regions for large hail is the mountainous northern India and Bangladesh, which have reported more hail-related deaths than anywhere else in the world and also some of the largest hailstones ever measured. Mainland China also experiences significant hailstorms. In North America, hail is most common in the area where Colorado, Nebraska, and Wyoming meet, known as "Hail Alley." Hail in this region occurs between the months of March and October during the afternoon and evening hours, with the bulk of the occurrences from May through September. Cheyenne, Wyoming is North America's most hail-prone city with an average of nine to ten hailstorms per season.

Hail is a form of precipitation which consists of balls or irregular lumps of ice (hailstones). Hailstones on Earth usually consist mostly of water ice and measure between 5 and 150 millimeters in diameter, with the larger stones coming from severe and dangerous thunderstorms. The METAR reporting code for hail 5 mm or greater in diameter is GR, while smaller hailstones and graupel are coded GS. Hail can occur within any thunderstorm, and is only produced by cumulonimbi (thunderclouds), usually at the leading edge of a storm system. Hail formation requires environments of strong, upward motion and lowered heights of the freezing level. Hail is most frequently formed in the interior of continents within the mid-latitudes of Earth, with hail generally confined to higher elevations within the tropics. Hail formation is preferred during the summer months in the afternoon and evening hours of the day.

Hailstones often grow in alternating layers of rime and glaze, when they are continuously rotated up and down by updrafts and downdrafts. The freezing process repeats itself until the weight of the hail stone causes it to fall to the ground or the updraft weakens enough to eventually end the cycle. Unlike ice pellets, hail stones are layered and can be irregular and clumped together. Hail is composed of transparent ice or alternating layers of transparent and translucent ice at least 1 millimetre (0.039 in) thick, which are deposited upon the hail stone as it cycles through the cloud multiple times, suspended aloft by strong upward motion until its weight overcomes the updraft and falls to the ground. There are methods available to detect hail-producing thunderstorms using weather satellites and radar imagery. Severe weather warnings are issued for hail when the stones reach a damaging size, as it can cause serious damage to automobiles, aircraft, skylights, glass-roofed structures, and most commonly, farmers' crops. Hail is normally produced by tornadic thunderstorms.

TEXAS TALE: The Mother of all Hailstones The largest hailstone ever imagined fell (with some help) in Texas sometime in the 1930s or 40s. It was featured in Robert Ripley's popular syndicated newspaper column and it's a most unusual, amusing and thoroughly believable occurrence — once you're given all the facts ... It seems that one gray and rainy day a traveling salesman (let's call him Earl) checked into the Raleigh hotel or another well-known Waco hostelry. As he checked in, he asked the bellhop to bring a block of ice and some ginger ale up to his room. (A common request for the time - when half-pints of beverage alcohol outsold all other sized bottles combined.) The ice was placed in the sink and after tipping the bellhop, Earl looked out at the battleship-gray sky that was fast turning black. As he watched, pea-sized hail started falling and then dime-sized hailstones. Soon it was quarter-sized and there were even a few stones of the (extremely rare) thirty-five cent-sized variety. The Wacoans who had sought shelter under the hotel's awning started gathering the ice marbles as they rolled within reach — marveling at the icy jewels. Earl (now well into his second cocktail) decided to have some fun. If the locals appreciated hailstones - he was just the guy to give them one they'd remember. He rounded the rest of his block of ice under the hot water faucet and gently lobbed the nine-pound sphere into the street. The people below were more than appreciative. They rushed out and picked it up as if it were a baby. They knew a world record when they saw it and within minutes a newspaper reporter was nervously stepping out of a taxi — running into the lobby before another nine-pound ice-meterorite could bury itself in his head.

Anxious to see the disappointment on so many faces, Earl went downstairs and fessed-up. But no one was buying the truth when the fiction was so much sweeter. Caught up in the excitement, even the bellhop forgot that he had brought ice to this man who was now frantically trying to admit to a hoax. The newspaper bought it — Ripley's bought it — and throughout WWII servicemen from McLennan County were telling the story of Waco's nine-pound hailstone from Rome to Okinawa. Only Earl knew the truth — but who wants to believe a salesman — especially when he's got liquor on his breath?