A sharp boundary between the warmth of Spring and the cold of winter often sets up this time of year. It fluctuates widely and is currently set up south of Tennessee right now! The warmth will push north over the upcoming days before another cold air push moves it back south. This is Spring.
Look how pronounced it is this Thursday! Temps will likely go from the 60s across the Region to the 40s in a matter of a few miles! Iowa and Nebraska see the sharpest of contrasts with 70s to 30s/40s across the state.
This is what makes forecasting fun this time of year.