Winter just likes to stick around in South Dakota. On this date, April 28, 1994, heavy snows hit southeast S.D. and the Minnesota-Iowa-S.D. corner with blowing snow after days in the 80s.
Source: http://www.crh.noaa.gov/fsd/?n=fsdtrivia04
On April 28th, 1994 winter returned to eastern South Dakota western Minnesota and western Iowa just three days after temperatures in the 80s and severe thunderstorms ripped across the region. A strong area of low pressure moved across the plains states and heavy snow developed across the tri-state area. Snow accumulated in the 5 to 12 inch range across eastern South Dakota with 5 to 10 inches in southwest Minnesota and northwest Iowa. Heavy snow fell to the crashes of thunder at Sioux Falls where 4 inches accumulated in one hour. The 10.5 inches that piled up in Sioux Falls was the most ever recorded for so late in the season.