We can't blame you for scratching your head if you checked the radar image Wednesday and saw what appeared to be a line of thunderstorms, yet looked out the window and saw crystal clear skies.
The visible satellite confirms there was nothing to be found:
Instead, I'm guessing what the radar was picking up was military chaff. It's the stuff that fighter jets give off to evade incoming missiles. Sometimes on clear days when the military is doing fighter jet exercises around the area, the chaff gets picked up on radar. Cliff Mass has a good explanation on it on his blog entry from May 30.