It is like an eastward trough of cold with warm edges as you move south out of it. I can remember that more than once, going from Erie down Route 11 on my Kawasaki 750, within two or three hundred feet I crossed an east-west wall that on the more southern side was about ten or fifteen degrees Fahrenheit warmer that you could instantly tangibly sense. I had come from freezing cold New York air east of Erie, PA to take-your-leathers-off warmth in Cleveland, far enough away from the lake trough to feel as if I had wound up in Florida, the change sharply defined about 30 miles below Erie.
Right now, the sun is shining in Wilmington DE, and there has been no snow on the ground since a week ago when we got an idiosyncratic six inches, but after it the snow disappeared the next day, and thereafter up to 58 degF on Saturday last.