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David J. Vercelli

One of the goals of the Automation of Field Operations and Services (AFOS) was to implement a computer program to automatically monitor aviation terminal forecasts at National Weather Service (NWS) forecast offices. Such a program has now been developed. The program can be initiated either automatically at predefined times or by the forecaster at any time. Once initiated, the program compares the information in the latest terminal forecast and surface airway observation at each designated terminal to a set of amendment and alert criteria. It then notifies the forecaster via an audio or visual alarm if any terminal forecast needs amending, or may need amending in the near future, due to changing weather conditions.

The program successfully underwent extensive operational field tests at four National Weather Service forecast offices during 1983. Analysis of the test results showed that, overall, the program performed very well and was found to be useful by the forecasters. In early 1984, the program was issued to each of the National Weather Service regional headquarters for use by the individual field offices. In response to evaluations provided by the forecasters during the field tests, an improved program was developed and is being tested at several forecast offices.

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Edward A. Zurndorfer, Joseph R. Bocchieri, Gary M. Carter, J. Paul Dallavalle, David B. Gilhousen, Karl F. Hebenstreit, and David J. Vercelli


In this paper, we present trends in the verification scores of the Techniques Development Laboratory's (TDL's) operational guidance forecasts and the National Weather Service local forecasts made at Weather Service Forecast Offices (WSFO's). Verification statistics for objective guidance and subjective local forecasts of probability of precipitation (PoP), precipitation type, surface wind, opaque sky cover, ceiling height and maximum/minimum (max/min) temperature are shown for the cool and warm seasons as these guidance products became operational during the period 1970–77.

TDL's forecasts are based on the Model Output Statistics (MOS) technique. The primary input to the MOS prediction equations comes from forecast fields from the Limited-area Fine-Mesh, Trajectory, and/or Primitive Equation models. For some equations, surface observations and other variables such as station elevation are also used as predictors.

Verification shows that through the years TDL's aviation/public weather guidance forecasts have compared very favorably with local forecasts produced at WSFO'S. The guidance forecasts are usually better than the local forecasts for precipitation type, surface wind and opaque sky cover; the opposite is true for PoP, max/min temperature and ceiling height. The verifications also show that local and guidance forecasts have generally improved for all elements over the years.

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