It is a warm and humid morning around central Indiana. The temperature only dropped to 79° overnight and dew point temperatures (measure of moisture in the atmosphere) remain in the 70°s.
As temperatures increase today instability in the atmosphere will increase, especially at the surface, in eastern Indiana and Ohio.
This is computer model projection of instability at 3pm EDT.
A cold front will begin to sweep through the Hoosier state during the early afternoon. Behind the front, much drier air will begin arriving. However, the front will provide lift at the surface, which in turn will aid in thunderstorm development.
A few thunderstorms have already developed in southwest Indiana. Storms will continue to "pop" over the next couple hours in central Indiana. The storms will eventually evolve in to a line of thunderstorms while moving very quickly to the north/northeast towards the Indiana/Ohio state line.
Computer models suggest the line of thunderstorms reach the Indiana/Ohio state line between around 4pm EDT.
I think the highest threat for severe weather resides in Ohio and southeast Michigan. However, strong to severe thunderstorm are possible in the eastern third of Indiana.
The main threat from thunderstorms, especially once they develop in to a line, is damaging wind. A few storms may be possible of producing hail and a few tornadoes cannot be ruled out, especially in northeast Indiana, Ohio, and southeast Michigan.