In a few weeks I am unfortunately connecting through ORD (VCE-ZRH-ORD-STL) between an LX flight from Zurich and a UA flight to STL. My LX flight arrives around 3:30 and my STL flight doesn't depart until 7:45.

I have been tracking these flights and have noticed that due to the storms in Chicago, the 7:45 flight has been cancelled at least once in the last week and is usually 1 hour or more delayed.

While STL is my final destination and an hour delay (or even 3) wouldn't destroy my travel plans (although the waiting would be painful knowing how close I was to home), a cancellation is what worries me.

Should I try talking my way onto the 4:50 flight to STL when I land in ORD, given that the storms always tend to hit after 5 PM? It would be for 2 people which I know is more difficult than one.

I am also flying on a discount ticket booked through Orbitz (yes, stupid I know), so I would appreciate any advice as far as re-booking options should I find out sooner than later my flight is cancelled. For example, would I have a better chance of calling Orbitz to re-book me or would they leave me at the mercy of the airline?

I guess if all else fails I rent a car and drive to STL?

(Please keep in mind I am a recent grad, just moved abroad, and am attempting to build some sort of status on airlines but haven't succeeded yet, but will be flying about 30K a year between Europe and the US)