The Spaceflight Meteorology Group

Postflight Mission Summary for STS-86

October 20, 1997

Space Shuttle Atlantis shakes off weather threats for another Florida landing.

Commander Jim Weatherbee used most of the runway as he guided the Space Shuttle Atlantis to a late afternoon landing (17:55 EDT)(2155UTC) at the Kennedy Space Center (KSC) October 6, 1997. Crosswinds were just under the limit of 15 knots and low clouds covered 2/8 of the sky, below the limit of 5/8 coverage.

The launch of Atlantis September 25, 1997 at 10:34pm EDT (0234 UTC) had fewer weather problems. A line of thunderstorms moved through KSC six hours prior to launch. This stabilized the air and conditions cleared nicely. SMG CONUS Lead Forecaster Steve Sokol updated the RTLS forecast to remove rain showers one hour before launch, though a band of low clouds appeared 20-40 miles NW of KSC that was monitored by satellite and aircraft until it passed through KSC and was no longer a threat. TAL forecaster Rich Lafosse was faced with a strong upper level low pressure area but the TAL sites at Moron, Spain and Ben Guerir, Morocco remained "go" for weather, while the prime site, Zaragosa, Spain, remained forecast "no go" for low clouds.

Atlantis had a highly successful flight. Astronaut Dave Wolf relieved Astronaut Mike Foale on The Russian MIR Space Station. In addition to the successful docking with MIR, the crew performed 3.5 tons of science and logistical exchange and conducted a five hour space walk.

The landing weather scenario was a little more challenging. On October 5, showers and thunderstorms increased and affected KSC, mainly around 6 hours before landing time. However, though most of the showers were no longer a threat, bands of low clouds formed over KSC due to low level convergence in easterly flow, and caused wave-offs of both opportunities. Close coordination with an Atlas launch just two hours prior to the first shuttle landing attempt made it even more interesting.

On October 6, the weather team was tested as weather began deteriorating at the Edwards AFB (California), White Sands (New Mexico), and KSC (Florida) landing sites. A strong upper level low pressure trough and front was causing wind gusts to 35 knots at Edwards (out of limits) and weather balloons could not even be successfully released. Showers began to affect White Sands; and KSC had occasional broken ceilings around 4000 feet (well below the 8000 feet limit) and peak crosswinds over the 15 knot limit. Less than 90 minutes before landing the forecast was amended to "GO" by taking out the chance of broken clouds at 4000 feet. The broken clouds stayed west of the shuttle runway and the crosswinds were right at the daylight limit ranging from 12-15 knots as the shuttle rolled down the entire length of the runway.

Atlantis landed at 5:55pm EDT (2155 UTC) to wrap up a highly successful flight. This was the 18th of the last 19 shuttle missions to land at KSC, and the 11th in a row.

Lead SMG forecaster was Steve Sokol working his 77th mission, 14th as mission lead. Rich Lafosse was Assistant Lead and Doris Rotzoll was lead Techniques Development Unit (TDU) meteorologist.

Submitted by

Steve Sokol