When you hit 81 degrees in December, you know that any transition to a colder pattern isn't going to be easy. We really need everyone to stay weather aware Sunday.
I think heavy rain and flooding will be likely across western and northern Arkansas Saturday night into Sunday. River flooding will become an major issue as well.
A strong boundary will sag to the sough throughout Sunday as a new wave of low pressure develops over Texas and pushes to the north-northeast. The atmosphere will become unstable Sunday afternoon and evening, especially for areas across southern Arkansas. Maybe as far north as Little Rock. The main threat will be heavy rain and damaging winds. We will also have to watch for the possibility for a tornado or two.
This video goes into more specifics.