The Memorial Day Weekend Tornado Outbreak of 2004

This article focuses on the weather events of May 30th, 2004. On that day, almost 100 confirmed tornadoes were reported throughout the Midwest and the southeastern states, as well over 500 reports of severe wind damage and almost 200 reports of large hail.

On the morning of May 30th, there was a strong upper level low pressure system over northeastern South Dakota. There was also a strong cold front stretching from Minnesota, into Iowa and through Missouri. There was a warm front moving north through Illinois and Indiana.

Looking at the upper level maps on that day, there was a strong jet at 500mb moving in through the area. Looking at all the available data, the Storm Prediction Center went with a High Risk of Severe Weather at 7 am; it was later expanded to include much of the Midwest and portions of the Southern Plains and the Southeast.

The severe weather started out early that day, with the first tornado watches going up in Illinois around 7:45 in the morning. These storms consisted of a squall line that moved into the area, temporarily stabilizing the atmosphere for a few hours. Later on in the day the main show started with severe storms rapidly forming as the atmosphere destabilized enough for them to form.

Severe weather started firing in Missouri around 2:30 in the afternoon. These storms rapidly moved east-northeast into Illinois and started producing tornadoes. Over the next several hours, tornadoes raced throughout central Illinois and invaded Indiana soon after. The most dangerous of these tornadoes approached the Speedway in Indianapolis but there were no fatalities.

As Indiana was being hammered, these storms started merging into a squall line as the cold front approached; damaging winds became the primary mode of severe weather as squall lines typically do not produce tornadoes. This squall line soon stretched from Indiana all the way into Alabama at one point.

This squall line went on to produce many reports of damaging winds. Storms started dying after sunset with the heat of the day dissipating. At the end, this outbreak killed 5 people: 4 in Missouri and 1 in Indiana. There were comparisons made to the Super Outbreak in 1974 but that event had more killer tornadoes. This event, while it had a big amount of tornadoes, did not compare to the Super Outbreak as that one had much more stronger tornadoes.