What does GR signify in a METAR?

In aviation meteorology, GR is used in METAR reports to signify hail. METAR is a standardized format for reporting current weather conditions, and the use of specific codes allows for clear and efficient communication among pilots and meteorologists. Hail is a critical weather phenomenon as it can significantly affect flight safety.

Understanding the significance of this code is important for dispatchers and flight crews as it directly relates to the conditions that may impact takeoff, landing, and in-flight operations. The presence of hail can indicate severe weather conditions, leading to potential delays or changes in flight routes. This awareness allows pilots to make informed decisions about safety and operational considerations.

Other options denote different weather phenomena but do not pertain to the GR code. For instance, rain has its own specific code, ground fog is indicated differently, and gusty winds are represented by another unique designation. This specificity in meteorological coding is crucial for accurate weather reporting and operational safety in aviation.