 All of the deaths occurred on April 30, which is known as the 1967 Iowa–Minnesota tornado outbreak, or Black Sunday, to residents of Iowa and southern Minnesota.That day spawned a total of twenty-one tornadoes, devastating the towns of Albert Lea and Waseca, Minnesota.Beginning on April 30, 1967, a potent mid-latitude cyclone generated severe weather, including blizzards and severe thunderstorms, across a broad region extending from the northernmost High Plains and Rocky Mountains to the Mississippi and Ohio River valleys.