How should the wind gust information be encoded for a wind gust of 18 knots?

The encoding for wind gust information uses a specific format to convey both the gust speed and the unit of measurement clearly. In this case, for a wind gust of 18 knots, the proper encoding would be "G18KT".

This format is composed of the letter “G” which indicates that it pertains to gusts, followed by the gust speed expressed in knots (the designation “KT” is the standard abbreviation for knots). The inclusion of “KT” is essential as it provides clarity regarding the units being used; simply stating “G18” or “G18K” does not specify the measurement in knots, which is important for pilots and meteorologists interpreting wind data.

Thus, "G18KT" correctly communicates that the wind gust reaches a peak of 18 knots, making it the accurate representation for this weather observation.