The National Weather Service (NWS) Spaceflight Meteorology Group (SMG) provides weather forecasts in support of NASA Space Shuttle landings. The Space Shuttle weather-related Flight Rules describe the weather conditions that are acceptable for various planned and emergency landing situations. Under the flight rules, the Space Shuttle must avoid thunderstorms (including attached non-transparent anvils), lightning, detached nontransparent anvils less than 3 hours old, and precipitation by specified distances during landing.

Adhering to the Flight Rule weather definitions is very important when evaluating the weather-related Flight Rules. The Flight Rule weather definition of precipitation is defined as radar reflectivity of 18dBZ or greater. Flight Rule weather definitions state that cumulonimbus clouds (-20 degrees C or colder within any part of the convective cloud) are to be treated like a thunderstorm for Flight Rule purposes. The maximum reflectivity that represents the cloud edge according to the weather definitions is 0dBZ. These are some of the examples of definitions that are critical when determining if the currently observed regions of interest contain precipitation, thunderstorms, and/or thunderstorm anvils. Understanding observed weather conditions is important since most of the weather-related Flight Rules call for not only a GO forecast, but GO observed conditions at final decision time (approximately 10 minutes prior to launch and 90 minutes prior to landing).

Various tools used by the SMG to evaluate the weather-related Flight Rules will be presented. The primary software display system used by the SMG is the Advanced Weather Interactive Processing System (AWIPS). The Display 2-Dimensional (D2D) within AWIPS allows the SMG to easily integrate satellite, radar, and lightning data. The User-selectable Layer Reflectivity (ULR) radar product is used by the SMG to display reflectivity at heights that are above the +5, 0, and -20 degrees Celsius levels. SMG has created a satellite enhancement that delineates these temperature values on infrared satellite displays and a radar reflectivity enhancement that highlights reflectivity above and below 18dBZ. The Reflectivity Cross Section (RCS) radar product helps the SMG determine the vertical extent of showers, thunderstorms, and clouds in general. In addition to presenting the value of these tools, the challenges and limitations of using these tools for Flight Rule evaluation will be covered.