WGN meteorologist Tom Skilling isn't sure:
This winter could for a number of reasons follow the lead of the past several winters and end up near or below normal. It would have to work at doing so. Bucking a strong El Nino isn’t impossible–but it’s not an easy thing for nature to do either.
Air over the warm ocean waters also warms, and this appears at least one factor in the build-up of a ridge over western North America which has contributed to the diversion of needed precipitation away from the western U.S. while contributing to the ridging (i.e. northward “buckling”) of the jet stream which has kept us cold in recent winters with huge Great Lakes ice buildup. It wouldn’t be hard to imagine some version of this happening again this winter–and that would profoundly change the current “warmer than normal” winter season forecast.
So while one of the strongest El Niños on record will exert some powerful effects on North American weather, the climate change we've already experienced may exert even stronger effects. The El Niño could simply reinforce the persistent ridge over the western US that has caused the last few Chicago winters to suck.
Can't wait to find out...