A thunderstorm is a storm that contains both thunder and lightning. These storms can produce flash flooding, gusty winds, hail, and even tornadoes. The southern part of the United States has the highest number of average annual thunderstorms, especially those states located near the Gulf of Mexico and the Atlantic Ocean.
Kentucky typically sees between 40 and 60 thunderstorms a year, depending on the location within the state. Most of the thunderstorm activity is observed during the summer months.
Source: NOAA
During the evening of May 1, 2002, a severe thunderstorm moving southeast dumped a large swath of hail ranging in size from pennies (0.75") to softballs (4.50") across a large portion of Laurel County. Numerous homes and vehicles were damaged, especially in the town of London. In April 1968, reports of hail up to 5.00 inches in diameter and a foot deep were made near the town of Baxter in Harlan County.