What you're looking at is an outflow boundary (cooler air rushing out of a complex of thunderstorms) created from numerous thunderstorms to our north over Central Indiana this morning. You can see it oriented from southwest to northeast around Cannelton to just south of Salem, Indiana. The boundary had little to no impact on our weather, but sometimes they can help trigger showers and thunderstorms.
That boundary at the same time is almost intersecting a ring just northeast of downtown Louisville. What is that ring? It look like a bomb going off on radar, but it is actually several hundred thousand Purple Martin birds taking flight at the same time from their roost in Jeffersonville, Indiana. We've seen this roost most of the summer, but it will be gone soon as the birds migrate back south.