What do the initials "SN" in a METAR report primarily indicate?

The initials "SN" in a METAR report specifically indicate precipitation in the form of snow. This code is part of the standard set of meteorological symbols used to convey weather information succinctly in aviation reports. In METAR reports, "SN" is used to identify that snow is currently falling or has been observed, which is critical information for flight operations, ground handling, and overall safety in aviation.

Understanding these codes helps in making informed decisions regarding weather-related flight conditions. Other weather phenomena have different acronyms, such as "RA" for rain or "FG" for fog, and knowing these distinctions is essential for interpreting METAR reports accurately.