It is widely known that Eskimoes have some incredibly large number of words for "snow," with different terms for all the many types of snow one is likely to encounter when living as an Eskimo.
In Iowa in the 80s, we kids knew only two kinds: the powdery kind that wasn't really good for much, and the wetter, heavier kind that could be used for building snowmen, snowballs, or (in theory) a snow fort. The former we simply called "snow." The latter was known as "building snow" when I was younger, and "packing snow" when I got older.
When I moved to Atlanta, kids didn't seem to have a term for "packing snow," since they only encountered about one day every four years. I remember hearing people refer to having seen "the perfect kind of snow for building stuff," but that's about it.
A quick look around on google books shows that the term "packing snow" is fairly well known, but it doesn't come up in print all that often. I'm not sure there's an "official" term for good building snow.
What do YOU call it?