An Examination of a Tornado Producing Supercell Behind the Leading Edge of the May 8th, 2009 Historic Wind Storm in Southern Missouri

On the morning of May 8th, 2009, a large mesoscale convective system (MCS) formed over southeast Kansas and moved across the southern third of Missouri causing significant damage to structures and swaths of complete deforestation. Post-storm surveys revealed the damage was caused by large swaths of straight line winds estimated to be as high as 55 m/s-1 and at least 21 tornadoes. After 1330 UTC several supercells formed north of the apex of the bow and south of a large line end vortex. These storms were responsible for spawning tornadoes that were rated EF-1 or greater. The initial outflow appeared to be comprised of an arc of scattered to broken moderate to strong convective cells. We will examine one of the supercells which produced tornadoes approximately 20 kilometers behind a newly formed convective line on the leading edge of one part of the MCS. We will also examine why this supercell was still able to produce tornadoes despite what appears to be its atypical location within this convective line. Finally, we will discuss how this case challenges the current conceptual models and the resulting challenge to warning decision making.