Hail in Sioux County, North Dakota

A North Dakota state record tying hailstone of five inches in diameter fell at Prairie Knights Casino and Resort. The resort, and all vehicles outside, sustained severe damage from the extreme hail. One of these large hail stones crashed through the windshield of a car, injuring the two occupants. This tied the record size five inch diameter hailstone in Mercer County on August 3, 1969.

Large scale forcing associated with a dynamic upper level trough coincided with very strong deep layer shear and very steep mid level lapse rates to trigger rapid thunderstorm development and intensification across southwest and south central North Dakota. Thunderstorms began in the late evening hours of Tuesday, July 13th, and lasted into the early morning hours of Wednesday, July 14th.

Severe Thunderstorm Watch number 469 was initially issued late Tuesday evening for portions of southwest and most of south central North Dakota through the early morning hours of Wednesday, with rapid thunderstorm development across the southwest already underway. Tornado Watch number 470 was issued early Wednesday morning for far south central North Dakota as intense supercellular thunderstorms with very large hail continued to develop and move east across far southwest and south central parts of the state. The intense thunderstorms eventually transitioned from very large hail producers to damaging wind producers as they moved east of the Missouri River and towards and into the James River Valley region.

Multiple severe thunderstorm and tornado warnings were issued. Numerous reports of large hail, including a record tying hailstone, and several reports of damaging thunderstorm winds were received during this episode.

Damage from the very large hail was extensive and extreme. Hardest hit were Hettinger, Grant, Sioux, and Emmons Counties, where baseball to softball size hail fell. Some homes had hailstones crash completely through the roof. The large hail also killed several farm animals, and injured other livestock and pets. A North Dakota record tying hailstone, five inches in diameter, fell at Prairie Knights Resort located in eastern Sioux County. In addition, some areas in these counties experienced more than one wave of large hail. Later Wednesday morning, straight line winds up to 105 mph resulted in extensive damage over portions of Logan and LaMoure Counties.