Spot the cold front

I just took Parker for his evening constitutional, and discovered it's really warm out. My kitchen thermometer says it's 17°C, but the official temperature at O'Hare is 9°C. That's...unusual. In fact, here's what the weather near me looks like:

So, O'Hare and Midway, which are about 25 km apart, have a temperature delta of fully 10°C. If you look at a slightly more distant pair, say Waukegan and Gary, which are both on Lake Michigan but separated north-to-south by less than 100 km, the temperature delta is almost 16°C. That is one hell of a cold front.

And it's coming...this...way...