What does "SN" indicate in a METAR report?

In a METAR report, "SN" indicates the presence of snow. This abbreviation is part of a standard set of meteorological codes used in aviation weather reports, where each code signifies specific weather phenomena. The "SN" notation specifically denotes that snow is occurring at the time of the observation, providing crucial information for pilots and meteorologists about current weather conditions.

Understanding these codes is essential for interpreting METAR reports accurately, as they convey important data about visibility, precipitation, and other atmospheric conditions essential for safe flight operations. The other options refer to different weather conditions not associated with the "SN" designation in METAR coding.