When should a "G" be used in a METAR report?

In a METAR report, the letter "G" is used to indicate gusty winds when the wind gusts exceed the mean wind speed by a specific amount, and the mean wind speed is substantial. The correct choice states that "G" should be included if gusts exceed the mean speed by 5 knots and the mean speed is at least 15 knots.

This ensures that gusts are significant enough to warrant notation in the report, reflecting conditions that may impact flight operations. By using these criteria, the METAR provides pilots and meteorologists with critical information about potential turbulence and wind shear, which are vital for safe navigation and landing. The thresholds help standardize reporting to ensure clarity and consistency in aviation weather communications.