So I'm trying to find it here, but I distinctly remember "GR" being "ice pellets" many years ago. Did they change it, or did I memorize it wrong. I always liked that it was based off of the German word, "Graupel", since "Graupel snow" is a very specific kind of precipitation, and basing the dang code off of it should mean that's what it *is*, but nooo...
Looking on this doc, it's now very specifically "Hail", and "PL" seems to have been added from what I remember long long ago.
And from another doc...
"The METAR reporting code for hail 5 millimetres (0.20 in) or greater in diameter is GR, while smaller hailstones and graupel are coded GS."
Yeah, that makes sense. FACEPALM. I'd like to slap whoever did that.
Here's what Graupel looks like... and it's now apparently "GS" in a METAR... instead of "GR" it's namesake...
http://en.wikipedia.org/wiki/Graupel
Oh well. Doesn't matter much anyway -- I've always loved the ridiculousness of having GS, GR, PL, IC... and then SN, and SG.
I'm a weather geek and can appreciate the desire to have all of those as they can mean drastically different things are happening aloft... but I sincerely wonder how many official observers out there actually have ever used all six of those.
And of course, automated stations can't possibly figure out all of those types of frozen ice falling from the sky so the overall number of times you'll see all of those used is... virtually nil.
Seems like the list of METAR codes for "frozen ice falling from sky" is just a tad "over-engineered". Perhaps four of those are necessary, but not all six.