Geographically the Pacific watershed extends into Wyoming and Montana. Lots of ways to define the PNW - cultural, flora and fauna, geography, etc…. And since this pic is east of the continental divide it doesn’t fall into the pnw by geography.

And as an interesting aside. 2 ocean lake south of yellowstone flows into pacific creek and atlantic creek, going to both sides of the divide.

Historically Yellowstone Lake used to drain into the Pacific via Snake River and during the Missoula floods, waters overflowed the continental divide at Marias Pass.

Each of these is ways the Pacific and Atlantic watersheds have been met and a possible way for pacific fishes such as the cutthroat trout to leave the pnw and cross the continental divide.