What does FC represent on a METAR?

In a METAR report, which is an aviation routine weather report, the abbreviation FC specifically designates a funnel cloud. This term is used in meteorological reporting to indicate the presence of a significant weather phenomenon associated with thunderstorms, particularly indicating rotation in the cloud structure that may develop into a tornado. Identifying FC in a METAR is crucial for pilots and air traffic control to assess potentially hazardous conditions.

The other options do not represent the meaning of FC in the context of a METAR. While fog conditions might be indicated in a METAR report through other specific abbreviations or descriptions, and freezing rain is noted in different terms, neither frost clear nor the other options provide an accurate or recognized interpretation of FC in aviation weather reports. Thus, recognizing FC as funnel cloud is essential for understanding severe weather conditions reported in METARs.