Some cities in Central Indiana have already received an inch of rain, and some locations by Sunday morning will near five inches. The shelf life of the balmy air (upper 50s) expires soon due to the passage of a cold front, and expect to wake up to temperatures in the 30s and lower 40s.
Periods of heavy rain are expected to carry into the Saturday evening.
There is a risk of damaging wind (especially south of I-70) Saturday evening… possibly in the form of a squall-line. Don't be shocked to see thunderstorm warnings issued Saturday "if" the modeled atmosphere becomes reality.
3″ to 4″+ storm total rain amounts will be common along and south of I-70 by Sunday morning… where river and urban flooding threats remain highest.
There have only FOUR December days in Indianapolis since 1871 to have 2″+ rainfall. Saturday likely joins that club, and possibly makes a serious charge at the all-time monthly daily record.
I'm still holding out some hope that vigorous snow showers develop within strong Arctic cold air advection Sunday evening into Monday. This "might" be enough to coat the ground in spots, but falls short of what most wanted for Christmas morning.