It's not profitable for them to run in summer as Zermatt/Saas-Fee are near by, have better snow, and have shit like the Matterhorn to attract busses full of japanese tourists. Glacier3000 only has a massive snowpark, not even a proper ski slope. So they decided to open only in april, early may, end of october, november, december. These are the months that no other Swiss/Savoyard resort has a proper park set up.
I am riding there right now and the park is choice.
Best park skiing of the season.
After that heading up to Kaunertal until it closes on the 28th of May. Should be sick.
As for Les 2 Alpes, it has the best summer park hands down, but also the bussiest and the snow is crappy due to it's low altitude / southern location. In Les 2 Alpes u usually have 10 people waiting to hit each rail or box. Also those crappy French/Italians in Les 2 Alpes snake lines ALL THE TIME. It's a pain. You got so many people waiting at the halfpipe (which closes at 11 am) and far too many of those pricks snake the line.
Zermatt pisses all over it in terms of snow quality, and the Zermatt park is empty in comparison. The atmosphere is more chilled, everyone knows everyone in the park. In turn Zermatt is about 3-4 times more expensive. Same story for Saas-Fee. If you can afford it, Zermatt/Saas-Fee is where it's at.
