I received the following from someone who was due to fly int'ly back right around the time of the warnings.
"We were ready for pushback when they closed the ramp due to thunderstorms... Then came the tornado warning and we all had to evacuate the aircraft."
If all the aircraft due to take off were evacuated that would be one busy terminal, and ORD is all windows! Wonder if they have a spot large enough in the basement to accomodate thousands (thinking how we were all in the ballroom).
Cheers.