What does 'GS' indicate in a METAR report?

In a METAR report, 'GS' specifically indicates 'Small Hail/Graupel.' This term is used to describe precipitation that consists of small hail or graupel, which is a form of soft hail or snow pellets. These phenomena generally appear when the temperature is low enough for the water droplets in the cloud to freeze either partially or completely before reaching the ground.

Understanding 'GS' is critical for pilots and weather observers, as it provides information about potentially hazardous weather conditions. While other options might relate to different meteorological phenomena, such as haze or fog, they are represented by different abbreviations. Recognizing specific weather codes like 'GS' helps in accurately interpreting weather conditions for safety and operational planning during flights.