With crosswinds gusting to nearly 20 knots, NASA was forced to delay the shuttle Discovery's planned return to Earth today by at least 24 hours.

Even worse weather is expected at the Kennedy Space Center on Monday, raising the prospect of a diversion to California or, more likely, yet another mission extension to Tuesday.

"Brian the winds are not complying with us today, they're looking steady out of limits," astronaut Dominic Gorie radioed the crew from mission control around 12:20 p.m.

"The current and the forecast conditions are both no go and the conditions have mirrored the forecast almost exactly, so we have high confidence that that condition is going to stay the same for the rest of the day," Gorie said. "We're going to terminate our deorbit attempt at this time."

"OK, understand," commander Brian Duffy replied.

The astronauts then re-opened Discovery's 60-foot-long cargo bay doors, reconfigured flight software for normal orbital operations and planned to go to bed around 10:17 p.m. They will be awakened at 6:17 a.m. Monday.

If all goes well, Duffy and pilot Pamela Melroy will fire Discovery's twin braking rockets at 1:43 p.m., setting up a touchdown on the Kennedy Space Center's 3-mile-long shuttle runway at 2:51 p.m. A second Florida landing opportunity is available at 4:28 p.m.

In addition, Duffy's crew will have up to three landing opportunities at Edwards Air Force Base, Calif., with the first coming at 4:23 p.m. EDT. The deorbit rocket firing for the first Edwards opportunity would come just a few minutes before the burn that would set up the second Florida landing time.

But the forecast for Monday calls for high winds, low clouds and possible showers at the Kennedy Space Center. Conditions are not much better at Edwards.

"We're expecting a chance for some (low) ceilings there as well as a potential chance for some rain showers in the area," said entry flight director Leroy Cain.

"As you know, it's a little to early and 12 hours from now we'll know a lot more about both sites," he said. "But we do have both sites for tomorrow, we're going to look at them both real hard. The forecasts are both marginal at this point, but we'll come in tomorrow and see how it looks."

The astronauts had two opportunities to land in Florida today, the first at 2;14 p.m. and the second at 3:50 p.m. But throughout the morning, crosswinds at the shuttle's 3-mile-long runway kept building and by noon, they were gusting higher than NASA's 15-knot safety limit.

NASA managers did not activate Edwards for today's landing attempt. But given the current forecast for Florida, Edwards will be staffed Monday as an alternate landing site.

"The forecasts for KSC generally degrade over time and the forecasts for Edwards generally improve over time," Cain said. "The forecast for Edwards is really quite good for Tuesday. We're looking forward to tomorrow to see what we get with the understanding that Edwards is expected to improve even more the next day on Tuesday."

Discovery has enough electrical power, fuel and carbon dioxide absorbent to stay in orbit until Wednesday if worse comes to worse.

NASA managers want to get Discovery back on the ground in Florida if at all possible to avoid disruptions in the space station assembly schedule.

A landing at Edwards would cost the agency about $1 million and add more than a week to the shuttle's ground processing flow.

Discovery's next flight is a high-profile mission scheduled for launch Feb. 15 to deliver the space station's second full-time crew: Commander Yuri Usachev, James Voss and Susan Helms.

Discovery also will bring the station's first crew back to Earth. That crew, made up of commander William Shepherd, Yuri Gidzenko and Sergei Krikalev, is scheduled to blast off aboard a Russian Soyuz rocket on Oct. 31.