Taylor Peay added a third for the home side when he turned the ball home after another cross from Nanchoff caused havoc in the penalty area.
The Timbers came close to scoring a fourth minutes later when Nick Besler raided forward and drilled a strike towards the bottom corner, but Darlow made a fine save.
In the second half, Portland threatened again and Nanchoff came within inches of finding the net as he curled his free kick towards goal, but his effort clipped the post and went wide.
The Timbers did score their fourth goal of the match when Jeanderson raided down the right and lifted a cross to the back post for the run of Besler, who guided his header beyond Freddie Woodman into the net.
Newcastle got a goal back when Aarons teed himself up in the penalty area and powered an overhead kick past Justin Luthy to bring his team back into the game.
Aarons reduced the deficit further when he lined up a strike from distance which sailed past the outstretched hand of Luthy into the net to give the Magpies hope of salvaging a draw. However, the home side held out to secure the win over McClaren's men.