NOAA 2000-036
Contact: John Leslie


The space shuttle Atlantis is scheduled for launch this afternoon after being delayed by strong winds for two days in a row. NOAA's National Weather Service Spaceflight Meteorology Group, a small team of meteorologists at Johnson Space Center in Houston who provide NASA with weather forecasts for launches, called for favorable conditions this afternoon.

Frank Brody, meteorologist-in-charge at the group, said today's weather "looks very favorable for a successful launch." He said the main factor in the two-day launch delay was strong winds, which his forecast team said today reached speeds of 18 knots with gusts up to 30 knots. According to Brody, strong winds can force a launch delay, since they can impact the ascent or emergency landing.

Brody said his team brief NASA officials as close as 20 minutes before the time of the launch, which is set for 3:24 p.m. EDT from Kennedy Space Center in Cape Canaveral, Fla. "Based on what we tell them, NASA can decide to proceed, or scrub the launch, but weather probably won't not be a factor Wednesday," he added.

The group, which consists of nine seasoned forecasters, has been the official source of weather information for all human-space flight missions. "The group has provided a vital decision-making input into the safety of NASA's landing and recovery of human space flight operations since the early 1960s," said Bill Proenza, director of the National Weather Service Southern Region. "We are very proud of the longstanding service to this nation's spaceflight program by this NWS group."

The current group staff has a combined 50 years experience providing weather support for shuttle launches and landings. The group is contracted by NASA to support the manned spaceflight program.

Brody said rain, cloud ceilings and winds are the prime weather forces that impact a launch and landing. For instance, if wind appears to play a determining factor, as it did on Monday and Tuesday, a NASA reconnaissance plane – operated by an astronaut – will fly into the area above the launch space. The maximum speed for crosswinds is 15 knots, but if the astronaut is comfortable with a crosswind of 17 knots during a pre-launch fly over, then the launch-day wind limit is pushed to 17 knots.

(A crosswind is a gust that blows across the runway that can push the shuttle to the side as it descends onto the tarmac.)

"It's NASA's call ultimately," Brody said. "Our role is to offer them the most accurate weather forecast."

Brody said Tuesday's peak crosswind was 30 knots on the runway at the time NASA decided to scrub the launch. "That was way too much wind," he said. Brody explained that if a mechanical problem occurs as the shuttle ascends, NASA's mission control in Houston may direct a "return to launch site landing." (A return to launch site landing occurs 25 minutes after a launch at Kennedy Space Center runway.)

Between launches, the group provides weather training for flight controllers and astronauts, participates in NASA flight control simulations and prepares for future missions.

For more information about the Spaceflight Meteorology Group and an updated launch weather forecast please visit: