The largest hailstone ever recorded in the US fell in South Dakota on July 23rd. It weighed almost two pounds! NOAA scientists estimate the updraft required to keep it aloft exceeded 160 MPH!

During the late afternoon and early evening hours of 23 July 2010, thunderstorms developed over portions of central South Dakota. Several storms quickly became severe in an environment favorable for supercell thunderstorms. In particular, one very strong supercell thunderstorm moved southeastward across portions of Stanley, Jones, and Lyman counties. One of the hardest hit locations was the community of Vivian, South Dakota, where extremely large hail, destructive winds to 80 mph, and a brief tornado were reported.

A record setting hailstone was ultimately discovered in Vivian, measuring 8.0 inches in diameter, 18.625 inches in circumference, and weighing in at an amazing 1.9375 pounds!! This hailstone broke the previous United States hail size record for diameter (7.0 inches – 22 June 2003 in Aurora, NE) and weight (1.67 pounds – 3 September 1970 in Coffeyvile, KS).

via July 23rd Extreme Hail Event.

(h/t Mike Moss at WRAL)