Thunderstorms are an integral part of the Great Plains climate and provide a significant proportion of total precipitation. Lightning, moderate to heavy rainfall, strong winds, and frequently hail accompany these events. Thunderstorm season varies greatly from south to north, but it generally coincides with the growing season for crops, contributing to the rains needed for successful dryland agriculture. In the Central and Southern Plains, thunderstorms are most frequent in spring and early summer, with a secondary maximum in the fall. In the Canadian Prairies May through September is thunderstorm season. The number of days per year with thunderstorms ranges from twenty-five to thirty at observation stations in the Prairie Provinces to forty-five to fifty in Plains portions of Kansas, Oklahoma, and Colorado.
Some thunderstorms reach an intensity that causes damage and are referred to as severe thunderstorms. These storms may produce flash flooding and erosion, large hail, intense lightning, damaging winds, and even tornadoes. Rainfalls of several inches in an hour or less occur throughout the Great Plains. Hail is common in severe thunderstorms and may be large and/or abundant, causing heavy losses to both crops and property. Hailstones the size of softballs have fallen on numerous occasions, and the Great Plains holds records for the largest hailstones documented in both the United States (Coffeyville, Kansas, September 1970, 51.2 inches diameter) and Canada (Cedoux, Saskatchewan, August 1973, almost 4½ inches diameter).
Alexander Paul University of Regina