Actually, that flight was first routed South of its original flight path, in order to avoid a very large storm system in the mid-west. At that point, it still could not head straight to Newark, due to another storm system in Indiana.
They were originally flying a little more East, but then got routed a 'smidge' North, to avoid the system, most likely when the system didn't move as fast as they figured. As to why they kept heading North-East, instead of a more direct path from Indiana, I cannot tell.
If you (quickly) look at the flight on FlightAware.com, you can see the course corrections due to weather.
scratch the following, the TFR (temporary flight restriction) isn't until later this week.
Another factor for this flight, was that it looks like once they went North to avoid the weather in Indiana, when they came east of the weather, if they'd have gone straight towards Newark at that time, there is a NOTAM for a TFR in Western Pennsylvania. So they most likely were shunted farther North by ATC in order to avoid the TFR.