The Storm Data entry for the date states that approximately 20 funnel clouds were reported in this area and 8 “touched down”. There is a chance that more than 9 South Dakota tornadoes developed on this day but knowing where they began and ended can’t be determined.
The Spencer, SD F4 tornado of May 30, 1998 was 1 of 5 tornadoes produced by one supercell that tracked about 30 miles. This destructive tornado had a path length of 14 miles and hit the small town of Spencer (population at the time of 320) destroying most of its 190 buildings. 6 people were killed and 150 were injured. The tornado was estimated to reach a width of a mile.