Global meteorological analyzed input data is obtained from theNational Centers for Environmental Prediction (NCEP), USA at the National Weather Service, USA  which is the starting point for nearly all weather forecasts in the United States. These data is used as input to the ETA model which  is used to calculate a 3 days high resolution regional weather forecast. The global operational forecast model run at NCEP is the AVN model (AViatioN model). The AVN is run four times daily, at 0000, 0600, 1200, and 1800 GMT. As of fall 1996, forecast output was available operationally out to 72 hours only from the 0000 and 1200 runs.