If hailstones are reported to be two inches in diameter, what code represents this in a PIREP?

The code representing hailstones that are two inches in diameter in a PIREP is "GR 2." This designation utilizes the standard aviation shorthand for "grapelike precipitation," with "GR" indicating hail and the following number specifying the size in inches. In this case, "2" clearly conveys that the hailstones are two inches in diameter.

Using the correct code in a PIREP is crucial for communicating critical weather conditions to pilots, as it helps them assess the hazard level they may encounter. This specific code efficiently relays the size of the hail, which can have significant implications for flight safety and operations.