Storm clouds from inland thunderstorms appeared to be the chief obstacle, according to the report from Patrick Air Force Base.
The liftoff for the 12-day trip to the international space station is set for 3:49 p.m. EDT Saturday. If weather prohibits a launch Saturday, NASA most likely would try to launch Discovery on Sunday, take a break on Monday and then try again on Tuesday, Pete Nicolenko, NASA's test director, said Thursday.
The launch would be just the second shuttle flight since the Columbia disaster in 2003, which killed seven astronauts, and the first since the liftoff of Discovery last July.
Discovery's seven-member crew will test shuttle inspection and repair techniques, bring supplies and equipment to the international space station and deliver the European Space Agency's Thomas Reiter, a German, for a six-month stay aboard the orbiting outpost, the AP reports.
Astronauts Piers Sellers and Mike Fossum, a Briton, will make two spacewalks and possibly a third, which would add a day to the mission.
Outgoing US President Donald Trump does not accept the outcome of the November election. Trump has also refused to attend Joe Biden's inauguration ceremony on January 20