STS-122 ready for launch
"Liftoff is scheduled for 2:45 p.m. EST, which is the middle of the 10-minute launch window. The timing is precise so Atlantis can catch up and dock with the International Space Station.
Forecasters expect a cold front to move over Kennedy around launch time, bringing with it clouds and storms, resulting in only a 30-percent chance of good weather for liftoff. Further, there is a possibility that the front may stall over Central Florida, providing only slightly better chances for acceptable weather for launch attempts on Friday or Saturday."
more at NASA.gov