TAF Verification Focused Upon Operationally Significant Weather Changes

The National Weather Service (NWS) is testing a new terminal aerodrome forecast (TAF) verification program to better support domestic flight operations. The users of TAFs, i.e., air traffic controllers, pilots, and air traffic flow managers, require a verification system that samples observed and forecast data based upon operationally significant changes in the weather, as opposed to the current system, which evaluates a continuous sampling of weather forecasts and observations along the time line, regardless of how much the weather is changing. The new system focuses upon the ability of the TAFs issued for the busiest of airports in the United States to accurately predict these event changes as far in advance as possible. Two examples of operationally significant weather events measured by the new verification system are the onset and cessation of instrument flight rule (IFR) weather conditions. The timing errors of these forecasts at various lead times to the events are measured and scrutinized.

This talk will compare data between the old and new verification systems and explain why data from the new system produces lower hit rates and higher false alarm ratios for IFR conditions. In an inter-agency effort to improve air safety and traffic-flow management during adverse weather, national standards for TAFs have been developed by the Federal Aviation Agency (FAA). These standards use statistics from the new verification system. A huge gap presently exists between the reality of today's TAFs and the future expectations of the aviation community. Verification data outlining this gap will be presented. Some ideas for how the meteorological research and operational communities might use these verification statistics to start closing the gap will be presented.