Tuesday at 6Z:

The pressure contours are very tightly packed, along with a central pressure of 974 mb.  At this time the fronts show a very strong temperature gradient.

At 850 mb, the central pressure stacked over the surface low.  The surge of cold air clearly shows the advancing cold front.  And the large system which takes up over half of the United States and extends into nothern Canada.  The temperature gradient at this time over western Ohio is .048K/km.

At 500 mb, the sytem still has two closed contours around it.  The strong vorticity extends out to the area near the cold front.

The system only starts to tilt slightly as the 200mb level is reached, but it is only a slight negative tilt.  The upper air support seems to support this system.