Noun
METAR (plural METARs)
(aviation, meteorology) Meteorological Aerodrome Report, the aviation routine weather report; a specially encoded weather observation report.
The METAR reporting code for hail convert or greater is GR, while smaller hailstones and graupel are coded GS. Source: Internet
The United States metricated the data interchange format ( METAR ) for temperature reports in 1996. Source: Internet
Within METAR code, GR is used to indicate larger hail, of a diameter of at least convert. Source: Internet