Tornado outbreak and derecho of May 30–31, 1998

The Late-May 1998 tornado outbreak and derecho was a historic tornado outbreak and derecho that began on the afternoon of May 30 and extended throughout May 31, 1998, across a large portion of the northern half of the United States and southern Ontario from southeastern Montana east and southeastward to the Atlantic Ocean. The initial tornado outbreak, including the devastating Spencer tornado, hit southeast South Dakota on the evening of May 30.

Source: Wikipedia — Tornado outbreak and derecho of May 30–31, 1998 (CC BY-SA 4.0)