The best thing you can probably do is to go back and read the journal archives in that time frame. Then you can see the differing conditions we have. In a nutshell, we can have melting snow, almost no snow left, tons of snow and even big storms.
I'd say in about 85% of the years there is snow and they are still grooming. The main difference is that the sun is stronger, so the roads are all pretty much bare, which can make getting to and from the trails to your hotel or other places not on the trail a little noisy, with the carbides scraping the pavement.
Of course the upside is lots of sun and mild temps!
-John
