In the wake of morning thunderstorms, afternoon sunshine heated an already very humid airmass over west central Missouri and eastern Kansas on Tuesday, June 8 2010, creating a very unstable atmosphere over the region. A slow moving cold front reached a Wichita to Kansas City line by late afternoon, rapidly igniting a long line of strong, slow moving thunderstorms. While the threat of damaging winds and large hail were diminished by the vast number of storms that developed along the front, excessive rainfall quickly became a concern. Training, or repeated thunderstorms tracking over the same area, deluged portions of the Kansas City metro into Cass County. Areas from Overland Park, to Grandview, to Lee's Summit, southward to Peculiar, Pleasant Hill, and adjacent communities, were hit especially hard as two and a half to four inches of rain fell in just a couple hours. Interstate 435 near the Kansas/Missouri state line was turned into a river at rush hour, with water rescues conducted near Cleveland, Missouri to the southeast. In addition to the torrential rainfall, these storms were prolific lightning producers, with nearly continuous cloud to ground lightning, observed well into the early evening hours. National lightning detection network counts, showed total cloud to ground lightning strikes well into the tens of thousands, but thankfully no damage was reported.
The only severe weather observed in the region, was with one of the first storms that developed in western Johnson County Kansas. This long lived supercell storm tracked southeast into Cass county, and began to show signs of organized rotation as it tracked toward Harrisonville, prompting the issuance of a tornado warning. A brief tornado touched down along the south side of Harrisonville, producing roof and tree damage to a church carport, a commercial business, and a number of trees at nearby residences.