We're still a week away, so these extended forecasts are far from set in stone. On the contrary, we all know that they sometimes change within the same day, nevermind in an intervening week. But it's initial information at least.
Weather.com, Weather Underground, and Accuweather are all predicting a mostly sunny Wednesday and Thursday for Indianapolis, some clouds, highs in the 80s, lows in the mid 60s. The first two predict "PM Thunderstorms" on Friday, and Accuweather simply says "a thunderstorm around late". Late what? Well... ¯\_(ツ)_/¯; they don't say.
I like using the NOAA forecasts the best, but they don't extend their predictions out that far.
If these are even generally indicative, it says there's a good chance of rain at some point later on Friday. There are predictions that go out further, but those are probably too prone to change. At any rate, bringing an umbrella or otherwise planning for some rain at some point seems to be a good idea.