There may be a new world record for hail size. On July 23, 2010, large hail (see the two atached photos) was observed in Vivian, South Dakota. One of the hailstones unofficially measured 8 inches in diameter with an 18.5-inch circumference. The current record-holding hailstone was one that fell in Aurora, Neb., on June 22, 2003. The Aurora hailstone was 7 inches in diameter with a circumference of 18.75 inches.
Members of the National Climate Extremes Committee will meet this week to evaluate the South Dakota stone and determine whether it is a record (as noted by Jim Scarlett, weather service meteorologist in Aberdeen, SD). The committee that reports to the National Oceanic and Atmospheric Administration assesses the scientific merit of extreme weather and validates meteorological measurements.
According to the Associated Press "Leslie Scott, who found the possible record hailstone, said it lost about 3 inches because he was without electricity for several hours after the storm. Weather service staffers told him to put it in a sealed plastic bag and to stop opening the freezer door to show it to people, he said".
Hail from the storm led to at least five reports of people being injured on Interstate 90 when hailstones crashed through vehicle windshields.