The eastern half, around Bend and up the Deschutes, looks like Big Bend. Mt. Hood is in the Eastern half, as I recall. I skied there once in June, but it was very icy. And windy. And cold. They used the timberline lodge there as the outside of the hotel for the Shining, so it was a bit freaky staying there.
I have it in my head that it's a west slope, east slope thing caused by the Cascades, but I may be making that up. The Cascades may be in Kansas, for what I can remember.
Edit: I had confused my west and east. I have the same problem trying to figure out south and north when it comes to the cold part of Argentina. And it should be noted that the Timberline was freaky because I kept thinking I neede a Carl Yastremski autographed baseball bat, and all I had taken was a glove.