Upper Grouse is part of the Eagle Poma area on the front side, Hidden away from tourists.
This local hangout is easy to find, but you have to put in the work to get there.
It's pretty easy though, Just head to the top of the gondola, Exit and head right up the hill to the old Eagle Poma area.
Once you passed Race Pitch and the trees open up in front of you you're in Upper Grouse.
This sparse tree area has some small features and short cliffs which offer excellent skiing in a sheltered forest.
This area is great to explore and you can keep heading right to meet up with the old Eagle poma line.
This entire area is excellent and highly recommended.
If you had further right you can meet up with the Top of the World Express or continue down to the mid mountain junction and to the village below.