What does the "Z" in the time section of a METAR indicate?

In METAR reports, the "Z" in the time section stands for Zulu time, which is another term for Coordinated Universal Time (UTC). This is a standardized way of representing time that is not affected by time zones or daylight saving time.

Using Zulu time is essential in aviation and meteorology because it provides a consistent frame of reference for pilots and meteorologists worldwide, ensuring clear and accurate communication regarding timing related to weather conditions, flight operations, and more. This avoids confusion that can arise from local time variations and allows for synchronization among different regions and time zones.

The other options pertain to different aspects of timekeeping. Local time varies based on geographic location and can lead to inconsistencies, especially in international contexts. While military time may also align with the 24-hour clock system, it does not specifically indicate that the time is within the UTC framework. Greenwich Mean Time (GMT) is an older term that was largely supplanted by UTC, although the two are often used interchangeably in casual contexts. However, using the "Z" in a METAR distinctly identifies the time as UTC.