Colorado tied it at 1 in the 89th minute on Sam Cronin's strike from distance. But, after a nice toe poke from Ishmael Yartey in front of goal, Jewsbury slid a ball past goalkeeper Clint Irwin for the winner.
Portland (5-5-4), which has won two straight, snapped a two-game road losing streak and won at Colorado (2-4-7) for the first time in seven matches, going 1-4-2.
Gaston Fernandez scored in the 38th minute to give Portland a 1-0 lead. Maximiliano Urruti used a skilled individual effort to beat three defenders and fed a ball to an open Fernandez, who beat Irwin inside the far post.
Portland goalkeeper Adam Kwarasey recorded his sixth shutout of the season — tying him for second in the MLS — to help the Timbers move from ninth to sixth in the Western Conference.