Traore jumped on a failed clearing pass to rifle a shot past Jimmy Nelson and give the Sounders only their second win of the season.
Kansas City was part of a four-way tie for the lead in the Eastern Conference when play began Wednesday. New York and Houston maintained their share of the top spot by picking up victories earlier in the evening.
Seattle improved to 2-3-3 and climbed into a share of eighth place with Vancouver in the Western Conference. Kansas City (5-4-2) is now tied for third place in the East with Montreal.