Can there be 40% of the Weather Falling?

I keep hoping there will some kind of weather genesis today. The National Weather Service has a 40% chance of thunderstorms predicted for us. Being the weather nut I am, I have dutifully watched the radar all day hoping we would see some of those tell-tale signs of summer pop-up thunderstorms. The weather radar doesn't look very impressive at almost 4pm. The skies outside are starting to look promising, though, at the moment and that gives me some hope.