The Severe Weather Outbreak of May 4th, 2003

Michael C. Kruk and Michael L. Spinar
Midwestern Regional Climate Center
Illinois State Water Survey
Champaign, IL

On 4 May 2003, a series of powerful supercell thunderstorms accompanied by damaging winds, large hail, and multiple long-lived violent tornadoes struck the Central Plains States. The authors of this presentation researched the meteorological conditions present during much of the outbreak. This analysis included maps with hand-drawn contours of temperature, dewpoint, and wind speeds at various levels of the atmosphere, cross-sections through the most unstable regions, soundings, and numerical weather prediction model output, as well as satellite and radar images. The authors used these data to discuss the factors leading up to the outbreak and compared their observations with the forecasts issued by the Storm Prediction Center at the time of the outbreak. They also examined numerous individual storms while pinpointing on radar their associated mesocyclones and "hook-echoes" indicative of potentially tornadic supercells. Finally, a synopsis was given of the damage that occurred, the intensity of the various tornadoes, and the warnings that were issued by the National Weather Service.