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Model Output Statistics (MOS) forecasts are a statistical means of interpreting numerical weather prediction models to provide expected weather conditions. While MOS can provide valuable information for short-term forecasts and indicate weather trends, they are not suitable for operational decision-making, particularly when it comes to alternate airport filing.

When considering alternate airport filing, it is essential to use the most reliable and accurate weather data possible. The criteria for alternate airport eligibility often require more precise observations and predictions than what MOS can reliably provide. MOS forecasts may not account for localized weather phenomena or rapidly changing conditions, which can render them insufficient for making the crucial decision of filing for an alternate airport.

Therefore, stating that MOS cannot be used for alternate airport filing recognizes the limitations of these forecasts in critical operational scenarios, ensuring safety and adherence to regulations that require higher standards of weather data.