The primary observation code for reporting surface meteorological data in the U.S. is?

The primary observation code used for reporting surface meteorological data in the United States is indeed METAR. This code stands for Meteorological Aerodrome Report and is designed to provide essential information about weather conditions at airports and other meteorological stations. METAR reports include data on temperature, dew point, wind speed and direction, visibility, cloud cover, and significant weather events, which are crucial for aviation operations as well as for general weather observations.

SPECI is an aviation weather report similar to METAR, but it is issued for significant changes in weather that occur between regular METAR reports. TAF, or Terminal Aerodrome Forecast, provides a weather forecast for a specific airport for a set period, primarily aimed at assisting pilots in flight planning. AWOS, which stands for Automated Weather Observing System, is a system that collects and disseminates weather data but does not represent a code format like METAR does.

Therefore, METAR serves as the standardized primary reporting format for meteorological observations, ensuring consistent communication of weather data across the aviation industry and meteorological services.