Here's a 21Z surface analysis. The front is really not moving much across Oklahoma or Missouri, and it's not moving too quickly through the southern Texas Panhandle. Note the "Marfa front" (black dashed line). Still not much of a temperature drop immediately behind the front. Freezing line is up in southern Nebraska. Only an 11 degree difference between Amarillo and North Platte, Nebraska. Over the next 24 hours, the cold air will deepen behind the front (unfortunately, my wall may leak a little) over the next 24 hours. By the time it's moving across central Texas, the temperature difference across the front will be quite significant.
P.S. As I look at the map, I should have drawn the stationary front right across Ponca City in northern OK rather than to its south. Not redrawing it.
P.P.S. I couldn't stand it. I adjusted the stationary front north to over Ponca City.
http://wxman57.com/images/21ZSFC.JPG