When we shut down and I could leap out, I ran into the FBO for a peek at the radar and, sure enough, there was a nasty looking line of stuff to the west and paralleling my route home. This green-and-yellow thing snaked north from the Gulf of Mexico to, I think, Baffin Bay, and there were great big blotches of orange and red. Not good, but I was pretty sure I could do an end run on it. We expedited the paperwork and I mounted up and pointed 72B north, VFR so I could stay low and circumnavigate the showers that were forming along the route. All was well until I got north of Lexington and that encroaching-but-still-parallel line started curving to the northeast right over Cincinnati; CVG’s ATIS was reporting rainshowers with gusty winds and limited visibility. I picked up an IFR clearance from Cincinnati Approach, and the controller let me stay low at 3,000 feet. He was planning to vector me around to the northeast for the ILS 21L approach at Lunken Airport (LUK) but, seeing the rapidly advancing wall of gray-green off my left wing already obliterating the city, I requested and got a visual to 3R. Wind direction — unless it’s a hellacious crosswind — isn’t too important in the 180 with 6,100 feet of concrete.